lost my dual boot

[Robert Peaker]

I installed the disc, (operating within Vista) and had the dual boot working. For some reason the dual boot in Bio disappeared. I do not know where to look. I managed to bring up regedit but realized the file was not in windows. Can I fix this? I can not delete or reinstall ubuntu. Thanks.

[quixote]

I'm not sure what you mean:
"I installed the disc" which disc?
"(operating within Vista)" Do you mean you're using wubi?
"the dual boot in Bio disappeared" I'm not sure what you mean by Bio.

"Can I fix this?" Most likely, yes. Boot problems are usually just a matter of pointing the bootloader at the right files again.

"I can not delete or reinstall ubuntu." The system won't let you? Or you can't for some other reason?

What error message are you getting?

How is your system set up? How many physical drives? Which logical drives do they contain? Which OSes are on each one?