Here I have a list of things you can do to solve this problem.
1.Delete cache and cookies
3.Logout then log back in
4.Try playing on a different browser(I recomend Google Chrome.)
5.Try using a different computer
6.Your computer may have a virus.Scan your computer for viruses and then remove them
7.Go to start menu>computer>computer again>right click any one of your hard drives>properties>tools>check now>check the box that says “scan for and attempt recovery of bad sectors”>start>after it’s finished check the box that says"Automatically fix file system errors" and uncheck “scan for and attempt recovery of bad sectors”.Now do the same thing for all your other hard drives.
8.Try checking your internet connection.Slow or no internet connection can result in lag or no internet at all.
9.Chill and eat a cookie.
If you have any more questions please give me a privet message.