Yes you can, and you can get it here :-
Just note that Win 7 comes in two flavours - 32 and 64 bit - and the repair discs are different, you need the correct one for your system. If I remember correctly, the repair disc downloads as a .ISO image file which you will need to burn to a CD, but not the image file itself. It has to be 'converted' to the necessary Windows files for it to work. A very good piece of software - widely and freely available - for this is ImgBurn. If you look around BC, you will find several copies of detailed instructions of how to use ImgBurn by DC3 - his instructions are clarity itself !
To use the repair disc once you have it made, all you need to do is power up the computer so you can open a CD/DVD drive, pop the disc in and shutdown. Re-boot and it will ask 'Press any key to boot from CD'. Press any key and it should take you into the repair options as described in the tutorial referenced above..
If this doesn't work for you, then you are looking at doing a complete re-install for which you will need your install disc. But no doubt you have data on the computer you would like to keep, and a full re-install will wipe it. You can get round this by using a Linux bootable CD to get the system running on Linux to allow you to copy data to an external drive.
I, and many others, have successfully used Puppy Linux for this, which you can get here, along with instructions on how to use it :-
You create the disc the same way as the Windows repair disc and get it into the computer the same way - power on to get the disc in, then re-boot. You will then find a utility similar to Windows Explorer which will let you copy all your work, photos, music etc. to an external hard drive, thus salvaging your hard created work before doing a full re-install.