Hospital hair! Tackling knots & tangles

CC
Advice please.
 
Due to preeclampsia & emergency c-section, I've had a long stay in hospital, 8-9 nights.
 
My hair, which is straight & which I tied up, has gotten knottier & knottier as I've spent a lot of time recovering in bed. When I take the elastic out, my hair isn't falling down - it's mostly horizontal!
 
When I'm home this weekend, I'm unsure of the gentlest & easiest way to tackle the many knots.
 
If you are a hairdresser or just have advice, please share your thoughts! Thanks.