How can I fix my Koss dvd player?

I have a Koss dvd/audio cd player, model KD25. The dvd player doesn't play any discs, and will only read it but never go to the next step, then say no disc available. Will not play, fwd or rew, it is stuck on the reading mode. When the dvd player is put on, the reading seems also not clear but numbers seem scrambled and not clear to read. Also tried cleaning the disc, taking power cord off for about 5 minutes but nothing seems to work to fix the problem. When it is reading also the remote control and buttons on dvd player itself doesn't work. Can you please give me some instructions on how I can repair this problem with my dvd player to read, and play a dvd again. Thank you very much.