You have the blues because your toilet isn't flushing. Have no fear, replacing a flush valve is easy enough for any handy homeowner to accomplish and doesn't cost much either. Here's how to replace that toilet flush valve so you can get going again.
Take the back off the toilet tank. This is a heavy ceramic piece so don't lay it across the toilet tank and be sure to have a place to put it before you pick it up. If you lay it across the tank it may fall in and crack the tank making a huge flood in your bathroom.
Identify the problem. Move the handle, or the flapper valve actuator if you want to get technical, and see if the arm it's attached to is still connected to the flapper strap or chain. The flapper strap is a rubber strap that runs from the flapper valve at the center of the toilet tank to the handle. In older flapper valves, this might be a small chain.
Reattach the flapper chain or strap if it has become detached. Hook the flapper strap or chain to one of the holes that best opens the flapper valve. If this is all that's wrong, your fix is complete and it was free.
Check the flapper valve. A flapper valve is made of rubber and it tends to wear out over time. If your toilet is running and not flushing, it's probably because the flapper valve is not sealing properly.
Go to your local home improvement store and pick up a flapper valve assembly. Be sure you have a valve that will fit your toilet and follow the package directions to replace the flapper valve.
Turn off the water supply valve to the tank and empty the tank. Remove the old flapper valve and install the new one.
Attach the new flapper strap or chain to the toilet handle then push the handle to be sure it lifts the flapper valve. Turn on the water supply line and fill the tank. Flush to make sure your new flush valve is totally operational.