Uninstall ubuntu 9.10

[oz]

There's a way to reverse the 2nd dd command you said?

If you should want to recover lost partition tables and/or data, the best tools that I know of for doing that are TestDisk and PhotoRec:

TestDisk - CGSecurity

Both of them can be found on the Parted Magic LiveCD and they seem to work very well for the majority of users:

Parted Magic LiveCD

If you are afraid to do anything with your computer, you should definitely make some good backup images that can be used to restore your system if anything should go wrong. If you intend to continue running Linux, you can find some backup/recovery applications that might work well for you here:

Backup & Recovery | Linux App Finder

If you intend to run Windows only, I'd suggest Acronis True Image for creating system images:

Acronis True Image

[luismcrd]

ok,
I've already got a backup image to restore the system (which is the one and only dvd used to restore system) because I don't have a cd called windows xp, that should came with the computer. It's a master dvd (that block when the boot is made) which was done, when start to use the computer.

Thank you for your explanations.