Action button will no longer place blocks, open doors, etc. - it only destroys/punches

Have been playing the game for several weeks. Was playing as usual when "Out of Memory" screen popped up, was forced to quit the game. Tried to relaunch and continued to get the same message. The following day tried to launch the game again, and was able to get into the game but now the action button will not place blocks, open doors. The action button can now only be used to destroy items.

I tried to create the memory .bat file that is recommended on the Minecraft website (javaw -Xmx512m -Xms512m -jar minecraft.exe). I cannot get this .bat file to launch Minecraft.