The Verdict: Need More Info
This turns on whether you were born Polish and ever actually lost it. Take our ancestry quiz first; if you hold it, apply for a decision confirming Polish citizenship rather than for restoration.
Restoration is only for a foreigner who lost Polish citizenship, so filing for it would concede the very thing you may want to establish.
Since 19 January 1951, taking another citizenship has not by itself cost anyone their Polish citizenship; that needed a formal permission almost nobody sought. Since 1 January 1999 the only way to lose it has been to renounce it with the President's consent. Decades abroad on another passport usually change nothing.
A decision confirming citizenship is made by a voivode, or through a Polish consul abroad, with a six-month statutory time limit. Old documents carry it: a Polish birth certificate, a parent's Polish passport or identity card, a military record or a residence registration.