iTunes isn't finding my iPhone anymore. It did do to begin with, now it's stopped. Why!?!

My iPhone initailly was able to sync with iTunes.

For some reason, iTunes is unable to locate my iPhone.

When plugged in, it asks me if I'd like to download images/photos etc so it knows an iPhone is plugged in, but in iTunes itself, the left hand collum is blank.

I unplugged my iPhone & plugged in my iPod, iTunes found that fine, just not my phone.

I haven't added or upgraded the software etc, I basically haven't done anything different than I usually would.

Someone please help!