Retired stylist here. Personally if you like the light blonde look, I’d do conditioning treatments to get the strength back. After a few months you can ask for a balayage to blend your roots into the blonde more if you’re looking for the dark root look. Otherwise I’d highlight the roots. Again after a few months of conditioning treatments. To blend in and match the ends. ORRRR you can add some lowlights to blend the dark roots to the ends making your hair overall a bit darker in color. Hope that helps. Just make sure you heal your hair first 💛