Washing Machine Not filling
Some basic troubleshooting: the water has to be going somewhere. If the water is going in but not staying in, that means it's going out, and if it's not spilling out on the floor, that means it's going out through the drain hose. Can you see water going out the drain hose?

If so, is the outlet of the drain hose lower than the level of the washer's spinning basin? If so, then that's where the water is going. You've turned the whole washing machine into a big water level and one side of the level (the drain hose) allows water to escape, so it's escaping. Solution: raise the outlet of the drain hose somehow.

If the outlet of the drain hose is already higher than the level of the basin and water is still coming out of it, then it sounds like the pump is prematurely pumping the water out for no good reason. Can you hear the sound of the pump? I'll defer to someone who knows more about washing machine repair if this is the case?