My account is one of those affected. It wouldn't be so frustrating if it hadn't been going on for nearly two days now, without a glimmer of explanation. All my followers have been wiped off my profile, and so were all the people I follow. As of yesterday I could only see the updates of two people (thanks, @brynmorgan and @rachel_h, for keeping me going). All my own updates are no longer visible to my followers, because they're not following me anymore. I've re-followed a few people, but it's basically like going back to square one, or being wiped off the face of the Twitter earth.
Twitter becomes more helpful the more you use it - you find interesting new people and you build up followers who respond to your updates. It actually takes work and effort to find the people you like, so to lose them all is a bit of a blow.
I'd like to ask Twitter what on earth is going on, and why it's taking so long to fix it. I don't think people would mind if they just let us know, but since I've signed up to the forum thread on this issue I've seen dozens of updates from people in a similar position who are similarly confused. I sent an email to their support desk, and had a hugely unhelpful automated message back saying, amongst other things, "If you want to delete your account, log in and click the 'delete my account' link in your settings page." No, Twitter, I do not want to delete my account. You have deleted it for me. And you won't tell me why. I'd ring your press office, but you don't have one.
Strangely, the problem seemed to get fixed overnight, only for everything to disappear again first thing this morning. And several people affected have mentioned an account called @monkeybutler19, who mentioned me in a tweet around the time my account died. I'm sure there's a perfectly simple explanation but a little bit of communication would be very welcome.
Update July 24 - Last night there were a few hours where it all seemed ok again. But by this morning, after Twitter carried out its so called "correcting" exercise where spammers were removed from people's follower lists, all my followers and all the people I followed had gone. So my account has been wiped out. The same thing happened to a couple of people I found on the forum for technical problems. Losing these people is extremely annoying - they were really useful for my job and it had taken me six months to build them up. Twitter is still ignoring me.