Sorry to hear about your problem...but if that is the worse that happens on your boat, you are a lucky guy!
Perhaps some more specific information? It is not clear what you mean by "bolt". Or even "table"!
My dinette table support is a metal tube which fits into a bracket above and below. I have not taken them apart, but the brackets seemed to be screwed in.
The table itself slides up and down using a metal sleeve, and is secured in the correct position using a quick-release pin.
If the quick release pin is the issue, it looks like a ball-lok pin to me; WestMarine have a variety of lengths at
https://www.westmarine.com/buy/west-marine--ball-lok-quick-release-pins--P002_065_009_003?recordNum=1The metal sleeve clamps onto the tube; any bolt will do for that purpose, but ideally get something with a hand grip so you can easily tighten it; try searching Amazon for "star grip bolt"
Hopefully the answer you are seeking is somewhere in that!!