Lost access to Windows 7 Drive (Dual-Boot Windows 7 & Ubuntu)

I lost access to my windows 7 drive (Dual-boot windows 7 & Ubuntu). every time I try to run Windows 7 I get the message: Bootmgr is compressed, Press CTRL_ALT-DEL to restart. I could run Bootrec /fixmbr or diskpart or attrib to rebuild my mbr table through DOS command window using my windows 7 recovery CD. The problem I cannot access drive C: where my windows 7 are. I get the error message: Cannot open volume for direct access or system cannot find the drive path or specified. I still can access all my windows folders and files through home folder in Ubuntu. I don't want to reformat and reinstall windows. Is there is a way to run the DOS commands within Ubuntu or any other advice to how to fix this issue.

Thanks Golden. I did go through it, but with no luck. I still cannot find or open windows 7 drive C:

If the Bootmgr is truly compressed then you'll need to boot in using DVD/Repair CD to decompress the files to get it to boot as shown here: BootMGR Compressed Message at Boot Fix - Vista Forums

Once you know the files are decompressed if it still won't start then Mark Win7 Partition Active and run Startup Repair - Run 3 Separate Times.

GRUB can corrupt Win7 beyond repair in some cases, but to know you've done everything possible there are also these further steps for Troubleshooting Windows 7 Failure to Boot