I purchased it 11 days ago for $4.99 (75% off). When I wrote this review, the price was $19.99. But now it's $45. Probably when you update the price, old buyers lost their access.
It is rare is the first time they tell me that something like this happens to them, do you happen to have access to a product called updates, and if not you should contact the support of itch.io, because it makes no sense that by changing the price you delete everything.