grey areas at the bottom
These are often result of one of three issues:
File was cut off, truncated for some reason. Easiest way to tell is by comparing the file's size to that of an image shot with same device + settings.
File size = okay but when opened in a hex editor half the file consists of zeros.
Invalid data in 'JPEG bitstream'. Decoders interpret any FF xx byte pairs as JPEG markers. If the FF xx does not correspond with valid marker, most decoders stop decoding. This (1) is a result of that, (2), (3) and (4) are different stages of repair, rest damage needs to be corrected in photo shop or similar:
color/image shifts of some stripes of the image
Shift can also be due to corrupt data inside 'JPEG bitstream'.
Striped, harder to tell what you mean. If you mean like this:
Then we're dealing with loads of corruption in bitstream while these are result of mixed data:
In this case data was mixed due to a corrupt file system. The diagonal patterns suggest it's mixed with JPEG data that was encoded using different resolution.
Even loads of corruption can sometimes be repaired, but it can take up to hours of work per file:
Another variant of 'stripes' or maybe better said diagonal patterns can be caused by header not representing correct encoder settings, often result of incorrectly recovered files:
I happen to have screen-captured repair of this particular file here https://youtu.be/jhJtej2UI20
IF a file can be repaired depends on if the bulk of the JPEG data is preserved. How depends on the cause. The half grey image is repaired by 'patching' JPEG data.
We do not stand a chance to repair the Windows Explorer mixed data example, these will need to be correctly recovered.
Summarizing, we can only repair those in which JPEG data is largely preserved. File size is a give away as well as a quick look with e hex editor. If files looks okay and data inside file looks 'random' (high entropy) there's a chance it can be repaired. If you however see damage repeated file after file you may be dealing with a file system issue instead and it's best to try to recover the data to another drive.