Welcome to Fluther.
Since you didn’t specify, I will have to assume that you are not yet eligible to take distributions from your 401(k) by virtue of being at least 59–½ years old, or meet any other criteria that would enable you to take reduced-tax distributions. (I’m not sure, but I suspect that permanent disability would be a qualifying exemption from having the income taxed as regular income at that point.) I’m also assuming that you didn’t roll over the distribution, or you would have mentioned that. In addition, I’ll assume, absent qualifications to the contrary, that all of your contributions to the 401(k) were pre-tax. (It is possible in some plans to make after-tax contributions as well, and the return of those monies to you in the form of a distribution is generally exempt from additional tax, since you would have been taxed on the income at the source, your paycheck.)
Finally, I’m making another assumption that the tax that was withheld upon your distribution event was some kind of backup withholding that the financial institution is required to do.
You should file the tax return, because if this was your only income for the year (or a large part of it), then you may be eligible to have some of your taxed amount returned in a refund.
I doubt that you will owe the IRS additional tax on the amount of the distribution, but you gave no additional details regarding other income for the year.