I have a mp4 player and every time I turn it on it say insert usb line to use usbdisk then it say press any key to restart but it don't do any thing and when I do use the usb line it say format I hit format and it say usb disk after its done formatting

When I type I sometimes hit a key (I don't know which one) and a capital comes up and I can turn it back to a lower letter, I h ave tried the shift key and the capts lock and esc to no avail, also sometimes when I hit a key and I don't know which one the "underline" comes up and I can't get rid of that either, if someone answes please make it simple, as I am a senio citizen and not to swift..thank you