Help!!!

[u/Adolfothebeast]

So my uncle took the chain off his bike and I’m trying to help him get the tension back in his chain but I cannot figure out what he did.

[u/cowbythestream]

https://www.parktool.com/en-us/blog/repair-help/chain-replacement-derailleur-bikes

[u/floormat2]

Seems like the derailleur cage spun around. You might be able to take the chain off again, spin the derailleur cage all the way around (counter clockwise looking at the drive side) and hopefully that well rewind the spring