Sounds like your problem is in your directional switch if it's like the ones I've worked on. When you engage the four way flasher the direction switch is taken out of the circuit. I believe your four way has welded itself in the engaged position. You may be able to save your switch by opening it up and repairing it. They are fairly simple sets of slider type contacts. I would suggest you also troubleshoot what caused the blown fuse and switch problem. Otherwise, you may very well repeat what you are now trying to fix.
