I made a neder 8 years ago and only remembered it recently. Could I meikar hadin rely on the the fact that when I made Hataras Nedorim on Erev Rosh Hashanah I had forgotten making the neder so the hataras nedorim was chal then or does the neder get reawakened.
Thank you for your question.
The neder doesn’t get reawakened when you remember about it, and the Hatoras Nedarim of Erev Rosh Hashana did help. It is important to remember though, that the Hatoras Nedarim only helps for nedarim that we are allowed to be matir.
Elef Hamagen 581-101, also see Kol NIdrei 79-1 for the reason.