Before I installed linux, i had about 12-10 gigabytes available. When i installed linux and gave it 8 gigabytes of data. it was all fine and dandy. until i one day left my chromebook out. Someone else must've used it, because when i turned it on it was completely factory reset. i had to sign myself back in and update stuff. Then i got a notification saying i had 345 megabytes of data left on my chromebook! I went to storage, and i only have 1 gigabyte of data that is usable. I think whoever used my chromebook uninstalled it wrong, is there any way to fix it? It was Dual Boot Linux btw. I am looking to get my other 9 gigabytes back.
Try booting your chrome book with gparted live. You can get all the partition info and missing partition you mentioned there.
Be careful while restoring partitions, take the backup before you restore or create a partition.