PPC - Impression Stopped Coming

My PPC was running fine for 10 months, with over 800000 impressions per month and then all dropped down to 0 impressions. I genuinely had no idea why it’s stopped dead as it still were showing as “active” and “delivering” I tried all sort of solutions including changing the "Top of search" placements e.t.c..but no luck. The product and ad target were active as it always had been But still, non of these have worked for me.

Any suggestion please.