I was gone for a year and a half. I wound up with over 2000 and several levels’ worth of forgotten items.
What I should have done earlier but didn’t think of until I was nearly back is, figure out what level you are really at. That is, look through the recent levels in reverse order until you find the point where you remember most of the items. Then reset to that level.
This saved me a few hundred reviews and a lot of stress over misremembered items. Depending on how much you’ve forgotten, it could be even more. I would not, however, recommend a total reset. Unless you really remember nothing, it will only discourage you.
Whether or not you ending up resetting, the first thing is to simply sit down when you have some time to spare and go through reviews. If you have the ignore userscript, don’t use it. Simply let everything go by as quickly as possible. Don’t allow yourself to think too long about any single review, right now you only want to get through them. You can worry about the next reviews later.
Hopefully you can get through a few hundred in an hour this way, enough so that you can keep ahead of the returning reviews from things you miss.
Also, if you are struggling with motivation, find a way to force yourself to do reviews. If you have a commute twice a day, do reviews on your phone or laptop. Delete game apps or hide them behind layers of folders. Enable notifications that tell you when you get reviews and how many you have left. Leave WaniKani open front page on your computer. Change the desktop background to a Crabigator. Forget your usual hobbies and spend a little more time working through reviews until you get them all done.
In this way I managed to finally drop my total down to zero. Because of my reset, I had some lessons at the end, but I gave myself a day of rest after I finished reviews, to prepare for more WK. Give yourself time. You don’t have to get through everything immediately, but you do have to get through it.
(Looks at first post again)
Fortunately your situation doesn’t sound quite so extreme as many folks here have had. The only trouble is getting around to it. Even if you don’t have to resort to drastic measures, take the time to go through your reviews before starting lessons. I do recommend playing fast and loose with these reviews, because you’ll likely forget many of them.
Eventually, you’ll be back!
Good luck getting back on your feet. You can do it!