How can I go back to my level i accidentaly connected to somebodies else facebook candy crush level

We're sorry for your problem.

Most likely, your levels were not saved because your game did not sync to the server.

Please email Player Support so they can restore the levels manually on your account.

Go to the game's Start Menu, then Settings - Help Center - My Game Progress - Contact us and send them an email. Don't forget to mention what level you were on! 

It's important that you choose "Problems with my game" as your topic and "Game didn't save" as your subtopic. 

I hope you're back on track really soon! 

Also check here.