After upgrading kubuntu 7.04 to 7.10 cdrecord dissappeared

cdrecord has been replaced by wodim, although I have both cdrecord and wodim installed in Ubuntu Hardy (cdrecord from the multiverse repository).

Please look into the "Programs" settings in k3b and try the "Search" action from there: it should discover the required programs.
I guess that cdrecord has been replaced on your system with wodim, but the paths have not been adjusted.

Unfortunately, cdrtools have been removed from universe for unknown reasons and have been
replaced by a buggy fork called "wodim".

There is still a working recent original cdrtools in multiverse, you would need to install
it by hand.

Note that k3b prefers the original cdrtools because there are too many bug reports
with wodim.

Thank you for taking the time to report this bug and helping to make Ubuntu better. The package your reporting is updated and the issue should be reproducible with the live environment of the Desktop CD development release - Maverick Meerkat. It would help us greatly if you could test with it so we can work on getting it fixed in the next release of Ubuntu. You can find more about the development release at http://www.ubuntu.com/testing/. Thanks again and we appreciate your help.