Unfortunately, you'll have to trace the wires from the fusebox to the power window relay located behind the central console (where the heating and vent controls are) to the window motor. These wires are usually tucked away underneath plastic panels and carpeting, which means removing both if you want to get a good look at them. My car doesn't have power windows so I'm not sure exactly where they run. The wires also may be inside black sleeves meant to protect them from the elements, making it harder to check individual wires.

The ground wire for the windows is located on one of the screws behind that center console. Most ground wires are green. You'll have to pull out that console to take a look at it.

Do the other power windows still work? If so, the wiring and relay obviously works and may not be damaged, so there may be nothing to worry about. If you blow that fuse again, something is drawing too much power. That's when you'll have to start tracing wires. Fuses are designed to be the weakest link in an electrical chain and will take one for the team if too much power goes through it.

Check out this link:
http://www.vlvworld.com/indexframe.html?VolvoRepairManual/200_0_3.htm

It has a handy guide to what fuses go where and what they're for.

Below that is a diagram of some of the relays. #4 is the power window relay. It doesn't say what markings on the relay identify it as the power window one.
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Mike F - 1984 244 DL - 241,000 miles - Undergoing reconstructive surgery with POR-15