Best left to a gunsmith
Without knowing what is jammed, and not being able to see or examine your rifle, our only answer is to take the gun to a gunsmith.
Try Proofhouse.com
I have a Marlin 30 30 deer rifle and it is jammed with the lever action down how can I unjam it?
Millions made.
150
Blue Book of Gun Values
100-1000 USD or more depending on specifics.
A marlin lever action 30-30 rifle can hold fife shells in the magazine and one in the chamber.
Browning has made centerfire lever action rifles in various calibers over the decades.
Mossberg, mid '70s.
You will have to provde a detailed description of ALL markings and condition to get a realistic guess. Also, who made it.
You must provide a model number. 100-400 USD