There are many options for helpdesk software. It depends on your company needs and the way you'd like to organize your customer support. For example, you can try cloud-based solutions like GrooveHQ, or even Gmail based helpdesks like Deskun (we use it at the moment). Or maybe you'll need live chat software, there are also lots of it.
Hey there, you should definitely try Drag Team if you use Gmail. Drag is the simplest Helpdesk solution for small teams because it works from inside Gmail and integrates to the whole G Suite infrastructure. It's a Shared Inbox in Gmail and in Trello-like lists, so support teams can collaborate, drag'n'drop tickets and assign to teammates right from inside Gmail.
After all, support tickets are emails converted into tickets, that are converted back into emails for customers. So Drag allows simple teams to stay into their inboxes to solve customer enquiries. Hope it helps!