This ? https://www.mangago.me/read-manga/turning/
It's Korean btw.
Or this one? (It's also Korean haha)
https://www.mangago.me/read-manga/the_fallen_duke_the_knight_who_hated_him/
Btw this is also korean so Idk maybe this https://www.mangago.me/read-manga/how_to_raise_a_victim/
thanks for all your help guys but ive actually found it!!! its this https://www.mangago.me/read-manga/the_prince_and_his_mischievous_one/.
im pretty sure it was a (chinese?) bl manhua and the mc was blonde and a prince. the ml was this black haired guy and he killed the mc in the future. The mc regressed and stuff happened. This is such a bad explanation but u cant remember it to save my life