Took me a while to find but if you want to play on the server again simply follow these steps and dowload this
Link removed please refer to: http://minecraft.net/terms for more information regarding distribution of Minecraft filesFor PC Users1. Click the flag on the bottom left corner (start button)
2. Go down to the search bar
3. Type in %appdata
4. Click on .minecraft
5. Click on bin
6. Rename your old minecraft.jar to 1.4.6
7. Drag the recently downloaded minecraft.jar
8. Start up minecraft and play on your favorite server
For Mac Users1. Click on finder
2. Go to the top right in the finder and slowly type in library and look for the folder with a little temple on it
3. Make a shortcut to that on your desktop then click on it
4. Go to application support
5. Click on minecraft
6. Click on bin
7. Rename your minecraft.jar into 1.4.6
8. Drag the new minecraft.jar into the bin folder
9. Enjoy playing on your favorite server