Did you try the System Restore and the Startup Repair recommended in my first post? If not, you should do so.
SFC isn't completing which means that there's severe corruption on your system - so severe the program can't even complete.
Chkdsk isn't working so we can identify or repair any hard disk corruption (and it seems corruption is the reason it won't work).
You can't download any files for diagnostic or repair efforts (have you tried with safe mode with networking by booting and pushing the F8 key repeatedly until you get the menu and then selecting that option?). There's a hard disk diagnostic program I'd like to have you download and run to test the hard drive. To test your hard drive, check the manufacturer and then get the diagnostic utility from: http://www.techsupportforum.com/hardware-support/hard-drive-support/302602-hard-drive-diagnostic-utilities.html. If it fails the test, replace it. If it passes the test, then there's probably nothing wrong with it. If necessary, download it with another computer and transfer it to the problem computer with a flash drive and then install and run it (if you can - if you can't, post back).
Do you have a genuine Windows Vista Installation Disk or only a Recovery Disk from the Computer Manufacturer (or no disk at all except perhaps the one you may have made per my instructions to do the Startup Repair and perhaps even the System Restore - it can do it from the disk)? Do you have a Recovery Partition on your computer with perhaps a keyboard command to activate it (and do you know what that command is)? If you don't know the answers to these questions, you may want to contact your computer manufacturer to get the answers as that's pretty much the next step in troubleshooting. If you can get your hands on a genuine Windows Vista Installation Disk then that would be great because otherwise the only option is a clean install which neither of us would prefer.
We're running out of options. It seems to me that you have a bad corruption problem on your hard drive which is the root cause of all these problems. That may be repairable or you may need to replace the drive. That's the reason for the diagnostic program listed above - to check it out.
I look forward to your response.
Good luck!
Lorien - MCSE/MCSA/Network+/A+ --- If this post helps to resolve your issue, please click the "Mark as Answer" or "Helpful" button at the top of this message. By marking a post as Answered, or Helpful you help others find the answer faster.