Macbook stuck on startup repair

My MacBook Pro 2010 was sitting in a cupboard for a while. When i turned it on and says “unknown disc error”. Its running windows 7. It somehow booted up and now is stuck on the windows boot screen and performing something called “startup repair” for more than 10 hours. It says “repairing disk errors. This might take over an hour to complete”. What do i do now? Please help