The thing about Bach is that his music was inspired for its time, but it is hardly 'pushing the boundaries' to modern ears (this would be subject to a lot of debate, but I am entitled to my opinion). Try listening to some quirky modern music, e.g. Satie, Mompou, Debussy, Ravel.
If you have a piano, I find about half my ideas originate from improvising at the piano. Play a chord, and then just think about where you would go from there, and before you konw it you might have a piece. Also, embrace wrong notes- some great ideas come from them.
In fact, if you are a fairly good sight reader, I have found some great ideas from mistakes while sightreading Chopin Nocturnes and Grieg Lyric Pieces.
Also, it is better to start with melody rather than chords or harmony most of the time. That said, Stravinsky's 'Symphony in Three Movements' barely has melody.
If you are completely lacking inspiration, try writing a fugue. The guidelines of what you have to do to write a fugal exposition are so strict that half of the work is already done for you. I suggest looking up fugues before you write one if you do not know exactly what to do beforehand.
As the previous answer says, it is best not to try and force things.