You would have a dead short somewhere on one of those circuits. You could try disconnecting everything that is on that circuit and then put the fuse back in. Then start plugging things back in until the fuse blows.
That will be able to tell you what is stuffed then just replace it.
Don't put fuses 3 X the specified size. You could end up burning wires before you blow the fuse.
With the fuse out you shouldn't be able to measure 12v across it.
If none of that makes sense then you will need a auto electrician.