You are apparently missing a component libwinpthread-1.dll in your windows installation
This video shows how to 'fix' this issue,
https://www.youtube.com/watch?v=QggDVDlnwSM
but the real questions is How did this happen?
Sometimes it means that 'something' has messed with your pc. I would recommend you to do a in depth virus-scan of your pc.
Where (download-site) did you get your LMMS from?