how long 4charges 2b dropped on a bounced check citation if there was never any plea or admission of guilt?

Passage of time does not automatically result in dropped charges if a warrant was issued.  The relevant time period is from commission of offense to charging or from charging date until date of trial, excluding time that you were on a warrant or requested continuances, so long as the Commonwealth used due diligence to find you.  This is a complicated area so consult a lawyer with all the facts of your case.