Do you think something is wrong with my friend? What should I do?

I started talking to this guy about 2 months ago and since we started talking, we have literally texted nonstop all day until we went to sleep. We would chat on the phone, exchange video messages and pictures etc. We live kinda far apart so we have no actually met but have gotten very close over the past two months and planned to spend the weekend together over the 4th of July.

Things seemed great but last night around 7 when he was at work I fell asleep for an hour and have not heard from him since. It’s been over 24 hours and he said he was going out with friends when he got out of work but would still txt me and we were still on very good terms. Now I don’t know what to think, when I call him, it rings one time and goes to voicemail. I tried to call from another line to make sure it wasn’t a problem with my phone and it rings like normal. So I tried to call on my cell again later in the day and it rang like normal but now is doing the one ring and voicemail. I am concerned that something is wrong. I also thought maybe he blocked my number but I can’t imagine him doing this. I also can’t imagine that he wouldn’t e-mail me or try and contact me somehow to let me know there is a problem with his phone. I don’t know what to think, any suggestions? I feel like I might never here from him again, what would make someone just change over the course of an hour?