And in addition to the other two responses (!) if you were made an OP (@) by another OP then the chances are it was only temporary.
Most networks have some kind of channel service(s) whereby you can gain OPs in a channel automatically, or via a
/msg command. If a higher-ranking OP has not added you to the list of people that can do that, then you will remain deopped when you return
(Until/Unless someone OPs you again
)
Have fun IRCing.
Regards,