@ashkie12 There are a couple of things to note. First of all, you may have turned off the in-game shopping experience, which would otherwise try to sell you stuff while you're playing. The Sims 3 store is still very much active; you can check your account and redownload any items you've already purchased from the store site (https://store.thesims3.com/). By the way, it's actually a good idea to turn off in-game shopping, as it's a resource hog and can significantly delay load times in build/buy modes and CAS.
As far as your available worlds are concerned, with only World Adventures, Late Night, and Generations installed, you could start a game in Sunset Valley or Bridgeport; the WA and University worlds are not homeworlds and are only available through travel. (Adventureland is a phenomenon that suddenly appeared out of nowhere a year or two ago, and only for new installs that patched to 1.69, but it's just SV with only two sims living there.) But if you bought other worlds, they would also be in your store purchase history, and you could redownload them for free. Riverview is also available for free whether you ever installed it or not. Just make sure to sign in with the same credentials you used before.
Oh, and DCCache is where your installed store and custom content is saved. The game creates large master files of up to 200 MB each to store the content: .ebc files are from the store, and .dbc files are third-party content. So clearing this folder would remove all of this content from your game.
I don't know why your sim doesn't have the option to join the film career, but perhaps the building is borked. (Bridgeport in general is poorly built and presents a few annoying issues.) You could test this out by sending another one of your sims to get the job, or a sim from another household (no need to save the game afterwards). If your sim is the problem, maybe he or she would still be able to find the job in the paper or on the computer. If it's the building, you could bulldoze and replace the lot. Keep in mind that if there is no studio on the map for even a moment, even just within one Edit Town session, all the sims who were employed in the film career would lose their jobs. So it might be better to place a second studio before bulldozing the first.
Finally, a good troubleshooting step for any in-game problems is to drag your entire TS3 folder out of Documents and onto your desktop. All of your existing content—mods, store purchases, saves, etc.—will be preserved in this folder, but when you launch the game again, the new folder that spawns will not have any of it. If playing in this clean folder fixes whatever issue you're seeing, then you can start moving your existing content into it from your old folder, without needing to delete anything. When a bit of content causes the game to act up again, you'll know where your problem was.
