It's dead. -Fling it away and get another.
You can't but the tubes are less that £2 / bottle
Yes, you can paint hot glue after it has dried.
Acetone or nail polish remover can effectively dissolve dried Elmer's glue.
Yes, but it may not achieve much.
Some is and some isn't. There are thousands of kinds of 'glue' . -Name your glue, then we may be able to give a sensible answer.
You can tell if glue is dried by checking if it feels hard and no longer tacky to the touch. If the glue has a transparent or opaque appearance, it likely has dried completely. Additionally, if there is no odor coming from the glue, it is also a sign that it has dried.
The only chemical that dissolves it does more damage than the glue.
Yes, use epoxy.
Most household glues, like Elmer's glue, are not toxic.
generally you use a straightend out paper clip for inor breaks but more severe require a stonger solution such as airfix glue and a lollipop stick
Nothing happens
Name the glue - 'all purpose glue' is far too vague.