Hmn... If you haven't tried uninstalling-reinstalling, do that.
Otherwise, go to your install directory (example: C:\itch.io games\methods\Methods-1.0-win\game\BGS\chap62 ) and try deleting everything there. Then, in itch.io's client, go to your library, right click on Methods, and either check update or uninstall/re-install.
Viewing post in Release XXV // Chapters 61 & 62 comments
yup it worked i was afraid if i was gonna uninstaling this game i would lose it since i got this before the price came it was free at first but i reinstall it again and all 62 chapters are there so it worked thank god now i hope i wont have any troubles when chapter 63 and 64 show up but for now problem is solved.