Windows 7 Boot Mgr Missing - Please Help !!!

It is not usually advisable to plug a drive in after the system is on.

A "Startup Repair" is usually the choice for your situation. It runs the commands you have tried, but it may need at least 3 attempts to be able to repair a boot, if it can.

Since you have the system booted, have you tried just installing windows 7 again?

If your system will not boot with the drive, the drive might be bad.

And just to clairify, you are using your friend's computer with the one hard drive...

never plug a hard drive in with the power on, very bad idea. on restart you need to tell the bios to put the hard drive at the top of the boot order