Washer will not drain

If you have a top loader, try this.
If it agitates but doesn't spin or pump, it could be that your pump is seized or something is stuck in it. The agitator is operated by a different motor. Turn OFF the power. and remove the front vertical panel by inserting a drywall knife in a the top right about 4" in from edge at the joint 1" down from the top, push the clip back to release that corner, get another knife and do the same to the left top corner, the pull the top of the front panel and swing towards you, then lift off and remove. Discount the two hoses to the pump, one from the drum the other that goes to the back. Be ready for a considerable amount of water to come gushing out, use a hose to direct to a floor drain. Check to see if something is stuck in the pump or the hoses, remove it. Check to be sure the impeller spins. If you found something restricting the flow or pump, remove it and re assemble. If the impeller won't spin easily, then you need a new pump.

Remove blockage in the pump. Re-assemble and test.

If there is a drain problem, the parts that must be checked are drain hose, pressure switch, drain pump assembly, timer control.

Check if the drain hose at the back is kinked or blocked.

Test the pressure switch, blow into the small hose, and use a multimeter to check if switch has continuity.

Remove access panel and get to the drain pump hose to check for ablockage. You will need to disconnect the hose and collect the water.
On a GE front load, the pump is often accessible from front lower side of machine, on top loader is at the back.
Keep a container ready to collect water when you undo pump hose.

If all the rest is OK, test and eventually replace timer board. Problemwith water pump are far more commonly causing this problems thenfaulty timer board.

Parts and diagrams available here.