All writers experiance some "writer's block" from time to time. As stonepiano said, maybe looking at life thru a different set of eyes can help.
Sometimes, if you approach your instrument from a different way (use open tuning on a guitar, use an organ sound instead of a piano sound on a keyboard, etc) or even better, try to learn a new instrument - can create new inspiration.
In another post someone wrote - "write crap" - which simply means keep writing - something, anything. Making yourself go thru the process is a disipline which can help to harness the "muse".
There have been many times I was not inspired, but I still tried to write something, or develop a riff, or learn some new chords - and at some point I always stumbled on something that led to a new song.
Hang in there - and keep writing.