What can i do to a cavity in my front tooth until i see the dentist?

Not much: Avoid sweets, hot and cold foods. There are some temporary filling materials at drug stores, but they aren't helpful because the decay has to be removed. These are more for when someone has lost a filling.

Temporary filling: You can find kits in the drugstore that usually consist of a powder and liquid intended to be a self-service temporary filling. Mix it up and apply it to the hole but get to the dentist asap as the longer you wait to get it fixed, the more involved the definitive repair will be.