we can't see your k-1 and don't know what occurred in prior years. it's your responsibility to keep track of basis. if the return was prepared by professional preparers they may be able to provide basis worksheets.
also what year did it go negative? we can't say whether you have capital gain income or loss limitation.
here's a link to prepare your own but you may have to start with the first year unless your capital a/c has been kept on the tax basis.
https://www.thetaxbook.com/updates/TheTaxBook/Client%20Tax%20Tools/Partners_Adjusted_Basis_Worksheet...
