Hi there fellow gardeners. Could you tell me, is this image a Philadelphus?
If not, any guesses? Apparently it hasn't flowered in a while, probably due to pruning at wrong time of year???? Thanks.

looks like lilacs to me : )

Looks just like philadelphus to me. (Venation of leaves not quite right for Syringa, and usually syringa are thicker and shinier.) And yes, if you prune them in winter or spring you do lose the flowers. Prune immediately after flowering, so usually in about July, and preserve some new shoots that are forming, those are the ones that will flower next year.

Yes, could be Philadelphus but looks like a Deutzia as well, you will soon know because the former is scented and the latter not but in either case, prune after flowering,
Regards, Lannerman.

It's a common problem in these days and many peoples are worried due to this problem.I think you should share some pics to identify it.