In the so-called "iCDB" technology introduced in DxDesigner since the 2007 version, the Save button has been indeed removed because the database, which was turned from ASCII into binary, is written dynamically as you design. The Save has become an un-necessary step as well as the compile phase. Checks are performed dynamically too when possible or you can run a DxD Diagnostics command to detect more stuff. The errors reported by that utility can be fixed automatically on demand (from the output window).
Migration from 2005 to a recent version may require a bit of preparation. You can find a bunch of useful documents and video on Mentor Grpahics supportnet.
thanx for ur reply
If you have not already done so, archive your 2005 schematic and the convert the archive. This will get rid of that issue. Good Luck!