Going back multiple days on your save file solution (no mods).

[Keika]

A few days ago I left my game on the "end of day profits" screen whilst I went to my D&D session (stupid I know but what's done is done). I left it on winter day 14 and came back to it on winter day 26! My guess is my cat walked on the keyboard.
Anyway, I searched the internet for a solution without much success so I tried experimenting from what I could find.
Finally I found a way to go back to whatever day I wanted! I thought I'd post it here so other people could benefit from this. :D
The only downside I've found so far is I had a bunch of mail from days 14-26 but they appeared again when I got to the right day. Also I don't know what this would do to your crops since this happened to me in winter so please make a back up copy of your files before trying this!
On to the solution!

1. Press windows + r
2. Type in %appdata%\StardewValley\Saves
3. Find your save folder, it'll be named "your saves name_big number" make a backup copy
of this whole file somewhere just in case something goes wrong.
4. Open "your saves name_big number"
5. Press Ctrl+f and search for "dayofmonth" it should be the first result in a line of text the looks like this:
<dayOfMonthForSaveGame>20</dayOfMonthForSaveGame><seasonForSaveGame>3</seasonForSaveGame><yearForSaveGame>1</yearForSaveGame>
6. Change the day of month for save game number to the desired day.
7. Use Ctrl+f to find <shuffleMineChests>Default</shuffleMineChests><dayOfMonth>20</dayOfMonth><year>1</year> and change the day of month for save game number to the desired day/
8. Save and close.
9. Repeat steps 5-8 for the "your saves name_big number_old" file BUT set it for the day BEFORE your desired day (so if you wanted to go to day 10, you would change it to 9).
10. Repeat steps 5-6 for the "savegameinfo" file.
11. Repeat step 8 for the "savegameinfo_old" file (you don't need to do step 7).

I hope you find this helpful and I will be experimenting with this to see if you can go forwards and what it will do to crops!

Edit: Going forward in the game doesn't seem to work very well :/

[Bobywan]

Meh.
Winter is a slow month anyway. It's ok to miss a few days.
In your save folder there is a day-1 back up. I dont know anything else and cant help with your advanced solution.

[mooni]

this 2yo post just saved my life lmao. my cat unpaused the game while i was away for a bit and it jumped from day 8 to 15, most ppl said only going back one day was possible so i was losing hope ngl

it happened to me in spring so i can tell you what happened after i went back many days: all my crops and items that were grown/ready by the 15th were still there for me to harvest, even though my game was set to the 9th and some crops grew in 13 days. not really a downside since i got to collect a bunch of stuff that was still processing but oh well! it felt like cheating a bit but i wasnt gonna miss 7 days of spring like that.

thank u for the massive help!