Not much to go on here, but a group of teens solving mysteries makes me cast my mind back to A Pup Named Scooby-Doo. I know you said it's not Scooby, but consider this a variant? It matches the timeline and has characters with glasses y'know.

This is driving me nuts now too. A bunch of teens... glasses... mysteries... That's every other cartoon from back in the day! You sure it's not Scooby? Maybe think about other details, would ya? Like the show's style or specific episode plots.

Heads up, friend! This could totally be The PJs. It's not all about mysteries, but there's an episode or two that gets really close to that theme. And glasses? Fam, there's a character with goggles; maybe that's who you're recalling?

lol Eddy? Neddy? Why not Spaghetti? 😂😂 But on the real, it could be 'The Adventures of Tintin' unless ur memory's worse than my grandma's.

yo, maybe it's not exactly a 90s cartoon? sounds a bit like Dexter's Laboratory - Dexter had glasses and definitely had a Neddy vibe to his name. but that show wasn't about mysteries, it was more sci-fi wacky inventions.

Hmmm, if it's not Scooby-Doo and it's about a group of teens solving mysteries, could it be Martin Mystery? It's got that same vibe, and Martin wears glasses sometimes when he's disguised. Though the name's not Eddy or Neddy, the feeling fits the bill?

Could you be thinking of Fillmore!? It was about a middle school safety patrol that solved crimes and stuff. Had that cool retro comic style. Sound familiar?

omg dude, sounds like you're talking about Ed, Edd n Eddy! But they weren't solving mysteries tho, they were just getting into suburban shenanigans. Maybe you're mixing it up with something else?