If you only want the private certificate then following the requirements and doing the checkride as rudestuff says is the way to go. Getting a 61.75 requires a reasonable amount of work and patience these days. But your EASA vailidity isn't an issue - you are confusing validity and currency. As long as the 'based on' licence doesn't change licence number ( or is suspended/revoked etc) then it can be used indefinitely as the basis for a 61.75. You need to meet FAA currency requirements to use the 61.75 not EASA by the way.
But if you want the commercial then you will have to either do the private checkride first or get a private 61.75 cert first, because you are subject to the same requirements as anyone else taking a commercial
ie.
(h) Hold at least a private pilot certificate issued under this part or meet the requirements of
§ 61.73;
more here :
https://www.law.cornell.edu/cfr/text/14/61.123