Where is the filter located on my hoover AL120

i assume you're having problems with (probably hot) water intake into your machine. if so- either hot or cold-or both). there are 'semi-circle' mesh inserts at both your hot and cold water connectors on the back of the machine- you'll need to move your machine, if needed to allow access to these connections (where your hoses screw on). then, if you have shut-offs for the water supplies to your washer, turn them off! expect a little leakage from the hoses! if no shutoffs- turn off main water supply and open up an outside faucet, until it drains down! you may want to unfasten the water lines to the washer, and keep them elevated for a while until the water drains from them! (after doing the previous things!) you'll see- in the inlet s a mesh screen, see if they're 'crudded up' with mineral deposits- if so, get a hat-pin or some thing similar and pry them out- use an old toothbrush to loosen any deposits you see clogging them, and tap them to remove deposits! perhaps place them in a vinegar solution to help dissolve them! when they're clean- replace them- re-connect water lines- hand tight- or a little more- don't break the nylon outside threaded connectors on the back of the washer, or your looking at a more expensive and tedious job!
turn your shut-offs on, or your outside main shut-off, and hopefully, your drum will fill with great vigor!!
don't forget your outside hose faucet, if you needed to 'drain' it down! if 'outflow'- drainage is the problem then it could be a small article of clothing, or junk, in your drain pump- could also be a failed drain pump- you didn't specify whether it was input or output. just guessed!
good luck!!