Onboarding

I started at junior .Net backend position 3 months ago. I was assigned a mentor went trough initial meetings etc mentor gave me two projects to evaluate me I did them send them he said he will take a look and he will call tomorrow he never called so I messaged him he said he didn't have the time to look at them that was a month ago he went also on vacation for few days and the project manager that i was supposed to work with also went on vacation. I'm supposed to do these projects and then be put to work on a real project however none of that happened its like the company forgot I exist. I started working on personal projects again and watching courses because I'm bored. Its quite a large company. I don't mind doing nothing and getting payed but I don't know what I should do I never heard of this happen to anyone?