How to repair Windows' master boot record and fix your bricked PC

A nasty new form of ransomware is wreaking havoc on computers. Hackers that encrypt your files and demand money from you in the form of bitcoin is bad enough, but a few versions also overwrite your Windows PC's master boot record (MBR). The master boot record is a key part of your PC's startup system. It contains information about the computer's disk partitions and helps load the operating system. More recently, the Petya variant of ransomware has been causing MBR problems.