How to get a random (possibly grease) stain out of a dress. ?

[StillMedusa]

I have a dress I want to wear for a wedding. It appears to have come out of the wash with a stain on it that wasn't visible before! I have no idea what, or whether it was something in the machine, or something I didn't notice somehow.
Is there anything I can try?

If you think it’s grease / oil, then fairy liquid.

Try rubbing with neat washing up liquid then rinsing, works for grease

Elbow grease spray in the yellow bottles is fab for random stains, do a patch test first but it’s never failed me. I get it from B&M

Vanish bar (not liquid) works for most stains, but if your dress has been washed and dried the stain might be set now. Hope it isn’t!