Georgina Grogan said she was out shopping with her mother on Saturday when they decided to head into VeroGusto on Norfolk Row at around 5.30pm.
However, when Georgina asked to use the disabled toilet, she was 'shocked and suprised' to find coats, jackets, scarves and shoes inside.
Georgina, who suffers with chronic pain following a car accident two years ago, was also dismayed to discover that the lock had been taken off the door.
The mother and daughter protested to staff about the 'unnacceptable' manner of the disabled toilet before leaving the restaurant and later complaining to the manager.
Georgina then took to Twitter to express her annoyance, claiming that the waiter 'laughed at her', in a tweet which has been retweeted almost 400 times.
Writing in her blog, she said: "I’ve been disabled for a couple years now after a car accident and unfortunately I don’t get out a lot.
"On average it works out once every week and half, which means when I do go out, I like to treat myself, do something fun, and most of the time, try somewhere new.
We headed in VeroGusto Sheffield after walking past it a few hours earlier, it looked fancy, relaxing, and comfortable inside. The main thing on my mind was finding somewhere with an accessible toilet.
"I continued on to the actual toilet and I was shocked to see around 10ish coats in there, jackets, scarves, even a pair of SHOES!? ‘Is this a toilet or a changing room?’
"When I went to lock the door I was stunned to see that the lock had been taken off and there wasn’t one at all."
The owner of the restaurant, Saverio Bruno, said that three female kitchen staff used the toilet to change but left the items behind when Georgina requested to use it.
He said: "We had a bad lock on that door and, on that same day, a member of staff was blocked in by it. I did not want customers to get locked in the toilet so I decided to take it off.
"There is nothing sinister about this and I think they are taking it all too far and making a big deal about it.
"We let the woman in to use the toilet. We have had disabled people in the restaurant before and never had a problem."
Georgina said that she has been forced to completely avoid toilets when she's out as they are 'usually not accessable' for disabled people.
She said: "It’s a hassle when you have a chronic illness, they’re too small, the bins are in a stupid place, you can’t even get in without having to step over the toilet, the disabled toilets are disgusting, blocked off, or just generally too filthy to use. I’ve seen it all.
"It’s extremely inconvenient. A wheelchair user would have not been able to use the toilet (at VeroGusto) that has specifically been created for them."
Georgina took the incident to Sheffield City Council, claiming the toilets went a violation of the 2010 Equality Act.
A Sheffield City Council spokesperson said that they have spoken to VeroGusto and that the issue has now been resolved.
The spokesperson said: “We received a complaint about the condition of the disabled toilet on these premises. We visited them and spoke to the owner, and are pleased to say that the issues are being resolved.
”Under the Equalities Act (2010), premises have to make reasonable arrangements for disabled people, and we’d encourage people to report any concerns to us.
“We also work with organisations that champion the rights of disabled people, and have helped produce an online accessibility guide for venues across the city.
"This gives clear information about the facilities available, and is part of our ambition for a fairer and more accessible city for everyone."