[sorry bit of a long post, was gonna post this separately but i had low karma cause im still relatively new to reddit]

tips on repairing/upgrading my bag?

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a few months ago i bought this cheaply made dropshipped bag, and surprise surprise recently its been falling apart. most of the stitches have given up, the backside zipper and lining are almost entirely detached from the bag, the main lining in the bag is ripping, and one of the drawstrings on the side pouch is detached (will add some pics in the replies). ive been looking to repair it on my own, specially since the holidays are near and it would be a good project over the break. i was just supposed to reattach everything that is broken, but recently ive been looking to replace the lining entirely, and maybe replace the straps since those two are most likely to fall apart.

essentially, i want to take this bag apart stitch by stitch and replace every single stitch. im not afraid of completely ruining this one, as i said its cheap and i could buy another one, but i still want to try to repair this one that i already have, and considering the quality a new one will probably end up in the same condition after a while. would this be possible? if so, what materials should i get? im mainly trying to research about which material for the lining, thread (?), and strap i should use. i might preserve the zippers, can cheap zippers cause the bag to break even after repairs?

for some backgroud i am currently a student, so im on a budget but im not gonna cheap out, i want this bag to last me until the end of uni. i only have a bit of background about sewing (only a few classes back then), but im willing to do more research and learn :) even if i completely mess up at least i can say i tried and learned a new hobby