gpart almost worked, it recovered enough that i could manually repartition my drive correctly, and after lilo, the system booted and all is well...

Just let me say - always keep a copy of what your system returns when running:
fdisk -l
and:
fdisk -u -l
this displays as sectors not cylinders

This will help greatly with recovery - print it and file it, or at least store on another system, which is backed up!

Always remember - do not try to reinstall the system without this happening, and even when setting up a system, backup, backup, backup...

I have been working on our new web/database server to replace our existing one, it runs slackware.
After 3 weeks of configuration and re-writing web applications to work on the new server, and system (the old server had mail and proxy as well as web and database), I rebooted, only to get a message that the server will not boot... Doh!

Loading boot disks told me that the partition info had gone... I have not backed up yet... it is a new system and I had not got backup working and it is not yet live! I was rebooting to start the initial backup!

I have now found gpart - I should have printed out the partition info, again had not got to the documentation of the system part of the process - deadlines, switching between old and new projects, etc... anyway gpart is supposed to tell me the new partition types, I hope it does, or else I think I might just curl up and die... blind fdisk is my only other option

gpart has been going for some time, I have no idea how long the scan is supposed to take... will write more when it is done!