External CD Rom on laptop

I have wiped my Laptop and are now wishing to reinstall an OS but cannot get my External CD Rom to work. Have installed the DOS Drivers for it, do I need to load USB Dos drivers a well ? Also having problems with the A drive reading from floppys is this a software problem as well?
I have loaded all the command coms etc to C drive and it now boots to C: but thats it can’t get any further. HELP!!!!!!!!!!