You can copy out your files using the DVD or Repair CD with this method:
Copy & Paste - in Windows Recovery Console
You should have an Installation DVD. This is a major purchase which requires keeping the DVD for repairs as well as reinstalls. Go to your vendor and ask for the DVD which you are entitled to.
If Startup Repair will not find an installation then make sure the Win7 100mb System Reserved partition is marked Active using free
Partition Wizard bootable CD, highlight the Win7 Disk, from Disk tab run
Rebuild MBR. If this fails, boot into the DVD or REpair CD to try running Startup Repair up to 3 separate times with reboots.
If this fails, boot back into PW CD to try marking Win7 partition itself Active, again from Disk tab try Rebuild MBR, then if it fails to start try 3 separate Startup Repairs.
Try also from the Repair Options list running System Restore and from the Command Line try running
SFC -SCANNOW Run in Command Prompt at Boot and
Disk Check as suggested by Jonathan.
You've now done all you can to Repair Win7.
Your options now are to find a Win7 installation DVD for clean
Reinstalling Windows 7,
or have your brother save a Win7 backup image of his identical model Win7 installation:
Backup Complete Computer - Create an Image Backup, then boot the Win7 DVD Repair console or Repair CD to
Recover Using a System Image:
System Image Recovery. When it starts, copy in your data and change the Activation key to your own at Computer>Properties.