This can take two different paths, depending on whether you were 17 (a juvenile) or 18 (an adult, or were 17 but charged as an adult) at the time of the arrest. It would probably fare better for you if you were 17...but you were what you were at the time, and that can't change.
IMO, I agree with the prior poster. Call an attorney/legal aid and figure out exactly what your criminal record has in it. Once you know for certain what's on your record, you and the attorney can take the steps to address it and minimize any damage it may cause. You could try searching for your records yourself, but I never recommend DIY when it comes to legal matters. But that's just me.
As far as getting into nursing schools
...well, nursing schools have the right to accept or reject applicants as they please. And yes, your criminal record can factor into that decision. That doesn't mean someone with a record can't become a nurse; lots of them can and do.
Best of luck.