Q: why wont my iphone 4 reinstall in recovery mode

I'm trying to up-date my iphone 4.

It stopped working, was around 3/4 through the download / install and just hung up. After 24 hours I decided to shut down iTunes to try again!

Now when i connect my phone it has to recover as wiped everything and has to start again.

But now it keeps getting hung up around the same 3/4 mark on PC and half on phone screen.

I've tried to switch PC off and restart, switch phone off and restart.

HELP!!!