Help needed with a acrer aspire all in one Z3801 with malware problems

Please could anyone help re trying to sort out my sick all in one pc, for a few weeks now I have been noticing small changes like the DVD Rom drive stopped working but would play cd's and now I am having simple issues like being unable to log on to the wifi network (please note I use BT wifi to get on the net as I do not have my own Internet connection at the moment,) never the less never had problems streaming content or downloading files etc, today I've tried all sorts to try and find out what is the problem but am now stuck, I have a new win7 disc set but find the dvdrom stopped working , can load a Disc and hear it trying to start clicking and wiring but after about 10 seconds gives up, any ideas what I can do to get my pc working again. I can get into most services via run, also the diagnostics re the wifi not working gives a DNS not responding message when I run the troubleshoot tool,