Dvd rom wont boot

[minigamer]

I'm trying to reformat my computer but, for some odd reason it wont boot from the DVD ROM. I set up the bios to boot for the rom but, it still boots to the hard drive. The Rom is good I tested it on another machine but, wen put into the original machine it doesn't work.

 

[raybay]

Tell us the brand and model of your computer, or motherboard, with configuration... and particularly age...
Usually this is caused by a failed optical drive.
Why do you need to reformat it?

 

[minigamer]

I was gonna reformat because I was having issues with the OS but, I got it up and running with out reformat but, now it doesn't detect anything (mouse, keyboard,floppy,DVD ROM).. I'm using a dell l866r and yes I no it's old and probably not worth fixing but, I use it for my 6 and 8 yr old to play learning games and get a custom to a computer. I don't think it's the optical drive. I'm thinking maybe they did something to the registry but, without being able to use a mouse or keyboard I can't tell. Is there anyway I can get it to pick up the mouse and keyboard? Right now I'm at a lost. I've worked on comps for a long time and have never ran into this problem.