Computer not booting up

Hello,

I have a compaq desktop pc. it have been working perfectly for about 3-4 years. but suddenly the computer doesn't boot up.it have been recently repaired for this purpose.the lights and fans are working and the cd drive is also works. but when switched on the screen shows

AMBIOS(C)2011 American Megatrends, Inc.

BIOS Revision:6.07 BIOS Date:03/21/2011
CPU Type:Pentium(R) Dual-Core CPU E5800 @ 3.20GHz
CPU Speed:3.20 GHz/FSB Speed: 800 MHz
Cache RAM (L2) :2048 KB
Installed Memory:1024 MB/PC3-6400 Single Channel
Memory Bank 1: Not Installed
Memory Bank 2: 1024 MB/DDR3 SDRAM
Initializing USB Controllers . . .
Done.

After this nothing happens and stands like this for long time but nothing happens.
what can be done? please respond fast with all type of measures that can be done. THNX in advance :)
and one more thing the keyboard and mouse are not working.