Clocks should be in beat.  A clock that is not in beat will go tick,TOCK,,,,,,,tick,TOCK.  A clock that is in beat and adjusted correctly will sound a nice steady tick..tick..tick..tick.  If your clock is out of beat it may run for a while then stop, or run poorly.  If badly out of beat, the clock may not run at all.  Many modern clocks have automatic beat adjustment mechanisms.  Gently swing the pendulum all the way to one side and let it go.  You may need to try from each side, as the mechanisms wear they can get a bit uneven in operation.  Being in beat is not always the same as having the case level.  When I set up a clock, I level the case, then set the beat. In some instances, such as fireplace mantels, it may not be possible to get a clock perfectly level. If it is close to level, the clock can usually be put in beat.  A wall clock may have gotten bumped, or a recently moved mantle clock may have has sitting with a corner or two on matchbook covers that were mistaken for trash.  If too far out of level, the pendulum or weights my rub against the case, causing the clock to stop.  Some clocks, such as Banjo clocks, have very little room to spare.

Having the clock level front to back can be important as well.  If too far out of level, weights may hit the pendulum, or the pendulum may scrape on the case or other parts. 

Clocks should be on a steady firm surface. If they are on a floor that not level, shim under the feet until the clock rests firmly.  Tall cases may need a securing block between the case and the wall that is screwed to both.  For safety this is always recommended as people have pulled clocks over, but many people are adverse to putting holes in their clock cases or walls.  If you have a clock that stops at the same time every day, or the same number of days after winding, look at this closely.  When the weights get to a certain point in an unsteady clock, they can start to swing.  Once they start to brush the pendulum or pendulum rod the clock will usually stop.  Once it stops, the weights become still, and the cause of the clock stopping in not at all obvious.

When you moved your clock, you removed the weights I hope.  The most likely cause of this problem is mixed up weights.  If you have three weights, the heaviest goes on the chime train (right hand side from the front), the next heaviest on the strike (left side) train, and the lightest on the time train.  It is not unusual for the time and strike weights to weigh the same.  Please note that some clocks with very large pendulums have a heavy weight on the time train, and the lightest weight on the strike train.  Many manufacturers label the bottom of the weight to help avoid this problem.

If your clock always stops with one of the hands in the same place, or whenever the hands are together, one of the hands may be bent.  The hand(s) may be rubbing the dial, the glass, or on each other.  Carefully straighten the bent hand out, or call your friendly local clock repair guy.  If the clock always stops just at the hour, the striking mechanism may be jammed.  You can gently move the minute hand counterclockwise a few minutes at most then move it forward.  Do NOT move the minute hand back if you feel it stop against something.  Other than American time and strike clocks with a wire to adjust the strike, the minute hand can be turned backwards.  It is in fact the recommended method of changing time for modern German movements.If the problem is just a bit of dirt this may restore normal operation.  Realistically the odds are that a clockmaker's service is needed, but it's always worth a try.

Don't overlook the obvious.  Is the clock wound? 400 day or "Anniversary" clocks only get wound once a year.  When a clock gets wound this infrequently it is easy to forget winding is needed at all!  Wind you clock until it is fully wound. A weight driven clock should have the weights brought to the top of the case, but try to stop before the weights are pulled up against the top of the case.  A battery powered clock may have a weak or dead battery.  Old electric clocks have old plugs.  They may need to be plugged in firmly or have the plug replaced or the prongs opened slightly.

I'm sorry, but it isn't.  A spring wound clock may have dried up lubricant on the springs, a broken spring, or a broken ratchet mechanism.  Repair requires the movement be overhauled and the broken part(s) if any be replaced or repaired.  When a clock is fully wound, the spring coils are pressed into tight contact.  Old oil or grease can be sticky enough to keep the spring from unwinding and providing power to the clock.  If the spring lubricant is sticky enough to stop the clock, the clock is long past due for a thorough cleaning.

Clocks have various means to adjust the rate of the clock.  Many mantle clocks have a small adjusting post near the 12.  The winding key usually has two ends.  One end fits the winding arbor, the other end fits through this hole and couples to the adjustment mechanism.  Usually one full turn is approximately one minute per day.  Clocks with longer pendulums such as Ogee and Grandfather clocks have a rating nut on the pendulum rod below the pendulum.  Turning the nut to the right usually raised the pendulum bob, turning to the left lowers the bob.  Dirt and oil can sometimes cause the pendulum bob to stick to the rod.  You may be able to gently loosen this, but remove the pendulum first!  It's easy to damage the suspension spring if you twist the pendulum roughly.