update from 1.5.2 - 1.5.6 not working

The hosting site I use (bluehost) no longer supports php 5.2/3 so I need to update to php 5.4 - but my site doesn't work with php 5.4. I need to update my opencart to 1.5.6 from 1.5.2 and it didn't work manually (it erased everything) nor did it work with the auto update from bluehost.
There's something wrong and I can't fix it. I need to update but not overwrite my files. Please help.
Thanks,
Glenn

See PM in a moment (messages link top left on page).