Startup Repair running forever

I bought a refurbished Dell Optiplex i7 desktop and it came with Win7 Pro 64 bit installed, no CD of any kind. The other day it was running when the electricity shut off. When I tried to start it, after downloading files(?) it went into Startup Repair and after six hours of that I gave up and shut it down.

Besides the fact that I might have to let Startup Repair run for days (what's the point in having a computer that is disabled so easily?), I'd like to know if there is any other way I can fix this problem. Remember that I don't have the original disk.

I'm used to WinXP where such a problem just means that DiskCheck will run for 5-20 minutes and then it will start up. What's so different about Win7 that it can't handle something like this.

I hope someone can show me an alternate fix. Thanks... John

Thanks for the ISO Download link. I wish it worked for XP also, my other computer is WinXP and at the rate this is going, will probably stay that way. I'm going to try System Restore if I can get to it, I don't see any indication that Startup Repair is going to work for me. What's the longest time you've heard of it running to complete a repair?