This problem is arises many time when you are working with your computer suddenly files become corrupted and unreadable a computer file is just a set of data, organized in a way that programs can open and read it. If parts of the file’s data are disorganized or missing, then it becomes corrupted !
These problem occurs when you are not saving your file properly and sometimes suddenly power losses and more over dangerous virus and malware can harm your file . Try using antivirus if not resolve than you should use recovery tool .
There are various software available for recovering your file some of those given below !
1- Repair tool box.
2- Stellar file repair toolkit
3-Recoverit data recovery tool