A defrag shouldn't break the integrity data on a drive, as it doesn't delete data until it's written it elsewhere.
Yup connect it to the computer directly - if you know how. I don't think it can format unless you actually okay it.
There are some free data recover programmes about, but being at work, I can't find out what they are 'cos they are on the computer at home.
Sit on the problem for the meantime.