My photos and videos have disappeared

i went on my camera roll, and i saw that the majority of my photos and videos have disappeared. i used to have around 10,000 photos and videos and i upgraded to 50GB of storage, however i’m using 49.9GB. but now in my camera roll there’s only around 200 photos and videos. they go back to 20th may 2019 but there’s none after that. i turned my phone off and on again multiple time but they haven’t came back. my phone is an iphone xr, so it’s really new, i’ve had it since christmas but my photos were off a long time before that as i had them all on my icloud. what can i do to get them back?

​[Re-Titled by Moderator]