Where is this woman? I've looked everywhere that is possible and I've read online... but I still can't find her... I need her for the quest A Day to Remember... never married her.

2-3 hours just looking for her right now... I'm starting to think she is either a [censored] and got herself killed, or there is a bug...

(by the way... alchemy bug in my house is killing me, it spent 1,500 gold on that crap until I realized there is a Dawnguard bug hat prevents the alchemy house from appearing...).

Anyone knows where I can find Ysolda?

Cheers!
Umbra Diaboli

She walks the streets of Whiterun (around the marketplace), goes to the Bannered Mare in the evenings and to her house at night. Mark the quest as active in your journal, and she should have a questmarker on her.