My sansa express 1gb does not working

First, try a soft reset. Do this by pressing the center button and the up volume button simultaneously and try turning it on. If that does not work for you, you will need to get a micro sd card (it can be a dummy) and insert it into the slot on the side of the mp3 player. If you do not have one, you can use one of the round edges of a paper clip (be careful) to get it to come on. When you put either in, it should come on automatically, but if not, just press the power button. This should work to reset it. To charge it in a pc, just plug it up and it should come up. Then in a few seconds, it should start charging.