i feel awful saying this, but i am out of work, the last thing i can afford is a vet bill. so i hope someone can take me to a rspca.
Hi, when I first read the title of your post, my first instinct was that your cat is blind. Then, I read further, and it really sounds like she became blind suddenly. Eventually, she will adapt. It is easier for them to adapt when they become blind gradually. But, she will adapt. Just don't move her food or litter box. And, if you can help it, try not to move too much furniture. This will allow her to adapt much quicker.
Some causes of blindness, like Pip mentioned, are stroke, seizures, and high blood pressure. Kidney disease, which happens with kitties that are over 7 yrs. old, can cause high blood pressure. High blood pressure caused my cat to go blind, but hers was a combination of kidneys and some heart problems. A double whammy.
If this were my cat, I would take her to the vet, get some blood work and get the blood pressure checked. This way, you'll know where you stand and they may have you put her on some blood pressure meds.
Good luck and let us know how you both are doing.
It is entirely possible that kitty had a minor stroke or seizure, which has impaired her sense of balance. No way to tell without a thorough vet exam.
Some cats are lucky and remain healthy without yearly checkup, but we can help them stay that way longer if we do bring them in. Like well baby checks.