Replacing my m.2 ssd?

My adata internal nvme m.2 ssd has been getting stuck at 33% utilization but shows 100% usage in performance tab in task manager. I showed Reddit yesterday and was told my nvme internal ssd might be dying bc it shows a response time of 0ms, was told normal would be 1-20ms. It fluctuates up to 275ms iircc. It just started acting super slow this week out of nowhere, I try to download games and it says “DISK WRITE ERROR” and my pc starts lagging, mouse doesn’t even move and apps can’t open. CPU, GPU, 32 GB RAM all idle under 20% utilization. Interesting enough when this happens my external usb wdp40 nvme ssd disconnects.

My solutions so far : just cut power off then back on lmao

TLDR; what would the steps be to replace my internal nvme ssd, would I lose anything? How would I prevent losing anything in the process of replacing my ssd with a new one?