Hello,
if installing on the same hardware or at least with the same disks and with some luck (driver support etc) you can perform a server reinstall. This is a special installation mode, which wipes only the OS partition, user accounts, custom settings, but leaves the data intact.
In case this does not work, you can still get access to the data in the Shared folders as described in
this FAQ.
Best greetings from Germany
Olaf