Sun Solaris uses a UNIX file system (UFS), so you need your recovery to be specific to that file system.
UNIX Data Recovery works well with external media and can repair most major corruptions, damage that includes corruption with Inode Tables, Master Boot Record, Cylinder group header, etc.
UNIX Data Recovery should be installed on a Windows machine and then the Solaris drive should be attached for scanning and restoration. It also works very well with damaged external drives (even USB flash media). As always, a good backup is a good offense.