accidentally withdrew ucas

I impulsively withdrew my UCAS application, and this was after enrolment and everything. If I call UCAS and ask them to reverse this- will they be able to?

call UCAS asap, they could rectify it

This shouldn’t make any difference from the unis POV. They won’t be taking live updates from UCAS in regards to enrolled students.

oh my gosh thank you that is so relieving to hear. Only thing is, I cant log into my uni account as it says 'user doesn't exist', so do you think this will automatically change if its reversed?

Once you are enrolled, UCAS has no involvement.
There is no need or requirement to reinvent your UCAS account.

But I’ve lost access to my Manchester accounts

If you have formally enrolled at Manchester, you need to phone Manchester on Monday - this is a matter for that Uni, and something for them to reinstate, it has nothing to do with UCAS who are only there to facilitate your application. Once you are formally 'a student' at any Uni, they have no further interest in you..

Maybe I wasn’t like ‘formally’ enrolled? I think I had just set up my IT account and accom account and also booked it. However, I can’t log into those now. I was asked to fill out two forms- one was immigration and I did, but perhaps I wasnt fully enrolled at that point. What would happen then?

I impulsively withdrew my UCAS application, and this was after enrolment and everything. If I call UCAS and ask them to reverse this- will they be able to?

Hey!
I see you have had some very informative replies.
Just thought I'd add on since you were unsure if you had "formally enrolled". Based on personal experience, every year I receive an email asking me to enroll. This asked for similar details as you have stated. If you completed all the details requested on the enrollment, you should be enrolled.
However, you should definitely call Manchester tomorrow. If you're unsure who to call, contact either student support or admissions, their numbers should be available on the website. Simply explain your situation and I'm confident they will be helpful and provide you with the most accurate information, so try not to worry. 😊
I hope this helps, please feel free to ask me any questions,
- Sophia (University of Lancashire)