Hello.
I am using MS Office 2007 on my PC and I have several excel files which I always use at work. Naturally I used these files daily until recently. Yesterday I have faced an error while I tried to open my working files on Excel: Excel cannot open the file .xlsx because the file format or file extension is not valid. Verify that the file has not been corrupted and that the file extension matches the format of the file.
How can I fix this error?

Hi,
It sounds like you may have been infected by a virus. One such virus (Ransom-ware) encrypts all your files and charges you to un-encrypt them. I would look into such a virus CryptoWall HERE(http://www.bleepingcomputer.com/viru...e-information). A number of my clients had a previous incarnation of this virus and excel had the same behavior you described.

Good Luck,
Gus

hi,

Am Thu, 25 Dec 2014 20:44:07 +0000 schrieb YbricGrif:

I am using MS Office 2007 on my PC and I have several excel files which
I always use at work. Naturally I used these files daily until recently.
Yesterday I have faced an error while I tried to open my working files
on Excel: Excel cannot open the file .xlsx because the file format or
file extension is not valid. Verify that the file has not been corrupted
and that the file extension matches the format of the file.
How can I fix this error?

please have a look:
https://social.technet.microsoft.com...id?forum=excel


Regards
Claus B.
--
Vista Ultimate / Windows7
Office 2007 Ultimate / 2010 Professional

No Need to get irritate even if you are facing the Excel File corruption
problem,Or when you try to open it..

I can suggest to you can use Excel Repair Tool that can easily repair corrupted or damaged MS excel file without any trouble and restore complete data from corrupted or damaged excel file with in minutes. You can download free demo version from this site:- http://www.mannatsoftware.com/stella...el-repair.html