MacBook won't back-up, burn cd's and synch ipod

My MacBook was fine up until one day when it froze so I had to re install the OS, I downgraded from Snow Leopard to Leopard. Anyway, since that day it won't back up with Time Machine, it won't burn cd's, not mp3 or music cds and it won't synch my ipod touch. It always says there's something wrong with the disk (either the external drive, the cd or the ipod) that it can't be read from or written to. I don't know what to do, someone told me I need to format my hard disk and re install everything, but I don't even know how to do that, can anyone help me please?

G'day and welcome to the forums.

If the machine cam with Snow Leopard when new, that is the operating system you should install. If this is the case Leopard will not have suitable drivers etc. If it did not come with Snow Leopard, you may have a failed optical drive. Laptops, iMacs and Minis all use slot loading optical drives which do have a much higher failure rate that tray loaders.

So, if the notebook came with Leopard should I install Leopard after Formatting or can I install Snow Leopard? And if the optical drive is the one that's busted why does it burn dvd's? I don't understand!!!