iphone 4 will not sync photos to windows 7 now it suddenly quit working after march

why won't my i phone 4 sync to my dell computer with windows 7 now ?? worked fine up until march

i did not change any setting on my computer .. have been looking for answers online .. all suggestions have failed

verizon no help .. from day one i was able to just plug phone into computer and photos would download automatic

now i get " do you trust this computer " when i say yes it does nothing ..