How do I unlock car radio?

So I took my car battery out of my Ford Fiesta st 07 and once I put in back in and now it's locked me out, asking me for a four digit pin. However I don't know what the pin is. I don't have the manual and I've looked at every bit of paper work I have but can't find it anywhere.
So does anyone know of a way I can find out what the pin is without it costing me too much money? Is there something a regular garage can do or do I need to take it to an actual ford garage? The radio is the stock one if that makes any difference.

Don't know how Ford handles that specifically, but in general, you'll have to find a garage/dealership that can access the manufacturer's database (online or through a phone call). Usually, you'll also have to provide a proof of ownership and the car's VIN.

It's only 4 numbers so you have 10000 different numbers to try out.

Just call a ford dealership with your VIN number and someone should be able to look it for you.

Who doesn't keep the manual in the glove compartment.

You need the serial number of the radio, then ask here for your code.

Most manuals are available online. FORD FIESTA OWNER'S HANDBOOK MANUAL Pdf Download.

Typically the code is on a wallet sized card that is included in the purchase package when the car is first sold new. If you no longer have this card, then you have to take the car to the dealer, show proper ownership papers and they will tell you the code after looking up the VIN number in their records.