computer will not enter bios

[pevers31972]

Hi, This is the first time for ages I have been able to connect to this site, It was sometime last year that I had a problem with my power unit,this I did eventually replace,now powers up but now I am unable to get past this. \\sometimes it will show the bios screeen but then I am unable to use either the mouse or keyboard to get any further. I have tried to remove and replace the memory, remmove the back-up battery to let it clear,all have been no good. As I cannot even get a disc to run unable to restore Windows 7 Ultimate from the my windows disc. Anyone any idea s