Lost onboard sound card

[Pumpkin-55]

Hi
I've just put in 4gb DDR2 Ram (2 x 2gb)
System recognises just over 3gb (which I expected) and PC works fine, except no sound.
As far as I can see, it does not "see" any sound card so does not install drivers.
All I got in device manager is the std audio and legacy codecs but not the realtek HDA card it should see. Find new hardware fails to detect any card.
Tried to check BIOS to see if onboard audio still enabled but for some reason, although I can open the bios, can't use the arrow keys to adjust...it's as though the keyboard is dead. PS2 keyboard
Older computer..specs are
Windows XP SP3 32 bit
Foxconn K8M890M2MB Motherboard
AMDProcessor x86 Family 15 Model 67 Stepping 2 AuthenticAMD ~2599 Mhz
Radeon X1115 video card

Any advise greatfully received, even if to get into the bios adjustment so I can discount the thought that it's somehow changed.
Thanks for looking

 

[hang-the-9]

Reset the BIOS to defaults, unplug power, move the BIOS reset jumper to reset.

If that does not work, you can just get a cheap sound card for the system.

 

[Pumpkin-55]

Thanks for that.
I've solved it by removing one gig of RAM.
Seems like the system allocated space for RAM before sound.

If I can get into BIOS I may be able to change that but if not, I've only lost about half gig and can live with that.