I eraced all my contacts by mistake how do. I get them back!
And all other eraced messages as well.

Unless you have backed them up you are out of luck.

Not the simplest thing to do but might be feasible. Need a bunch more information

Computer type(pc or mac)

Which application are the contacts listed in

Email or something else

That's a good beginning

This recovery is a bit like surgery so you may need some side by side assistance on this.