My explorer doesn't have reverse now either but I didn't hear a popping sound

That is classic symptoms of *Low-Reverse* band failure - OR - failure within the band apply circuit .. Reverse is mechanically actuated .. It is not electronically controlled .. Therefore it is not possible to repair externally .. Transmission removal is required for rebuild OR replacement. Experienced 'mechanic' can quickly & easily confirm this by checking for *manual low* during test drive. 'This' is NOT a guess! ▪️https://repairpal.com/repair-shops▪️