Q.Why has my weeping cherry tree quit flowering?
My weeping cherry tree used to be full of pink flowers every spring but last year it didn’t bloom like normal. This year it only has very few flower buds on it. What could have caused this? Is there anything I can do to fix whatever the problem may be?

These past few cold, hard winters have been harsh not only on us but on the trees as well. A cold hard winter coupled with a cold spring sometimes is not a good combination for fostering budding/blooming on trees - it can delay the onset of budding/blooming or stop it altogether.
My best advice is to continue giving your tree TLC - guidelines on how to care for weeping cherries are in the article below. A boost of fertilizer may not be a bad idea.
https://www.gardeningknowhow.com/ornamental/trees/weeping-cherry/weeping-cherry-growing-tips.htm