Drawing file is not valid

Good day!
At work last week damaged the server. Today it was restored, but when you open an AutoCad file that lay on the network, gives the message «Drawing file is not valid». Before it is said that this file or is used, or only for reading. The file is not zero. Has the same size, as before crash of the server. I tried the command recover, drawingrecovery, insert. AutoCad 2008 version.
Very much I ask to help! it is a pity for the whole month of work!
Thanks in advance!
6 Answers

Hi Otto Cech!
you said your drawing file has file size and says that it is on read-only state. Have you tried right clicking the file itself and look if the the checkbox on attributes, read only/hidden is on/ has a check? Because it supposed to not have any box checked to be accessible.
see attached image below.
right click on drawing file and look for attributes checkbox
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If Your file opens without any errors, but part of the drawing's objects or all the objects are gone, and You are absolutely sure that it is not deleted them, then this most likely indicates the presence of the error file. It is necessary to execute verification of the drawing:
File -> Utilities -> Audit, either type in the command prompt: _.audit
On request: "to Fix any errors detected?" must be answered "_Y".
When the operation is completed (usually not more than 10 seconds) at the command prompt displays the log of test and the number of all found and fixed errors. Next, for display on the screen of changes, it is necessary to perform regeneration:
View -> Regen all at the command prompt: _.regenall
DWG Recovery Kit also helps to do dwg file recovery.
https://www.oemailrecovery.com/dwg_recovery.html
Good luck!

Comment about 1 months work.
If you don't backup (elsewhere) for a week, you are prepared to lose a week's work.
Backup your dwg to a thumbdrive or another computer on network.
Files systems aren't forever, but we wish.
OneDrive is a good offsite safe place, as well.
Sad about your loss?, or did you get it all back?
Does the file have any real data in it? or just a directory link to some junk?
It still may be recoverable.