Boot device not found

Your "boot device" is your hard drive.

This device shipped in 2015 with a HDD. HDDs for the consumer market (i.e. what would be found in your laptop) typically have a usable lifespan of 5-10 years. If yours is still on the original HDD, it is most likely an EOL failure.

The best solution would be to backup/clone your data, if at all possible, and replace the HDD with an SSD. I recommend Macrium Reflect free version (https://www.macrium.com/reflectfree) to do your backup and cloning, as it is easy to use, and their forums have experts on their software to help if you run into any issues.

This would involve physically opening the bottom of your laptop, locating the HDD (looks like this: https://thumbs.dreamstime.com/z/front-ba..., though the label can be any manufacturer), and remove it.

Then connect it to another computer with an external drive adapter (looks like this: https://i5.walmartimages.com/asr/b494567...), and image entire drive.

Then with your new SSD (looks like this: https://m.media-amazon.com/images/I/617e..., though the label can be any manufacturer), connect it to your computer where you stored your imaged drive (if applicable) and restore the image onto it.

Finally, install the SSD back into your laptop where the HDD was originally, close it back up, and turn it on.

At that point, if you were able to successfully create an image from the HDD and restore it to the SSD, you've got two possibilities: It will boot up exactly as it did in the past (but much, MUCH faster), or it doesn't. If it does, congrats, you're done! If not, you'll need to start debugging, starting with the easiest which is running chkdsk/sfc/dism on the drive, and creating a Macrium Recovery media (https://knowledgebase.macrium.com/displa...) to "Fix Windows Boot Problems" if that doesn't work, and then, if still not, but you DID get a successful image and restore, then there is something else going on that will require specific diagnostic.

If you were not able to successfully image or restore your original drive, then you'll best be off by installing the new SSD without the data, using a Windows Install Media (https://support.microsoft.com/en-us/wind...) to put your OS back on your computer, and then transferring over your personal files without your programs or OS. Do this by connecting the old HDD to your laptop with the previously mentioned adapter and transferring files directly as if it was an external hard drive or USB drive.

Finally, if you are not able to connect to your drive at all using an external adapter (and just in case, try a different one to make sure it is not a faulty adapter), then it most likely means you have a failed drive. Any data on that drive and not backed up elsewhere is LOST FOREVER unless you send it off to a data recovery center. This is expensive (around $300usd minimum, several thousand high end) and is NOT something you can do at home.

If you are uncomfortable or unwilling doing any of these steps, take it to your local repair shop who will undoubetedly do practically that exact procedure just with confidence and without having to buy new tools and equipment.