You could see if the cd boots on another machine - the machine you used to burn th iso for example.
If it does - then the cd is fine.
In that case, problem is with the sick machine - the optical drive, possibly.
You need the bit version that is the same as the o/s on the machine you are trying to fix.
Inexplicably, MS have made the system recovery options bit version specific.
However , both the 32 and 64 bit iso images are bootable - so check on another machine to see if the cd boots.