Wierdly enough, I have found one way to get inspiration, but it's not very nice..
Catch a cold.
I know it sounds strange, but during the "pre-cold" gestation period, when the viruses are sneaking through my body and the antibodies are mustering to the general call-up, my brain goes into some sort of sideways area. At the time I don't realise I'm coming down with a cold, that makes itself obvious about three days later, but during the build-up I suspect there's a great deal of chemical action going on internally and that's what triggers my "creative" period.
Don't recommend it as a general cure for artistic block, tho.

I agree with the "don't try and push it" advice given above.
A method I sometimes try when in a blocked situation is do something else entirely that I also enjoy. Go out and take photographs. Wander around the town centre. Chat with people. Go birdwatching. (Those are not suggestions for you, they're things I do.)

I also agree with Pakled's suggestion of playing with words, sometimes I notice a phrase and suddenly see it in a different light (a classic example of this is the phrase "Time Flies", which can be taken in several different ways, including using a stop watch as the flies negotiate an obstacle course)...

Cheers,
Diolma

(Who is currently trying to throw off a cold..)