Is there an expression of $f^{-1}$ in terms of product-log or other special functions which holds for $x>1$?
WolframAlpha finds the solution: $$g(y)=-y\,W\big(-\mathrm e^{-1/y}/y\big)-1,$$ which however only holds for $-1<x<1$, $0<y<1$.
Edit: Corrected $g(y)$ as per @jjagmath's comment.
As user1337 said in his comment, you just need to consider the other branch of the Lambert function: