The purpose of a bridge rectifier in electronic circuit is to convert the ac voltage (wave) into Dc voltage.
Usually it is located near the ac supply area. It can come in the 4 separate diodes arrangement or in a single package as seen from the photo. The specification that you need to know for a bridge rectifier are the peak reverse voltage (PRV) and the ampere. How do we know the spec of a bridge rectifier? By looking at part number printed on the body. The part number usually start with KBLXXX and you have to search a data book to look for the specification. Always replace the bridge rectifier with the same or a higher specification.
If you have the time, you can always join four separate diodes to form a bridge rectifier. Use the general purpose part number such as the 1N4007 to make a bridge and sometime this rectifier can even work better than the original one.
Whenever a fuse open in electronic equipment, you must always check the bridge rectifier. Chances is high that the bridge may go shorted too. If you experience enough, you may check the bridge rectifier while it is still on board. If you are a beginner, i suggest that you remove the bridge and test it with you multimeter. In Monitor repair,usuallly a replacement of a fuse and a bridge rectifier will restore to normal operation.