Sims 4 won't open

mlemcf​  For the white screen, please provide a dxdiag.  Click Windows key-R, enter dxdiag in the run box, wait for the scan to finish, click "Save all information," and save the file to your desktop.  From there, you can attach it to a reply using the paper clip (Attachment) icon included with the other formatting buttons.

For the missing pack, did you buy it outright, or did you originally get it through an EA Play Pro or Origin Access Premier subscription?  The current offer doesn't include Kids' Room Stuff, but the old one did, as well as Dine Out, and people who've maintained their subscriptions since before the offer changed are supposed to still have access to these two packs.

If you do think you bought it outright, please check your Order History on ea.com and see whether you can find a record of the transaction.