Social media is a mixed blessing in terms of evidence for your case.
It is worth looking for photos or videos on Facebook, YouTube, Twitter, etc that are helpful to your case.
There may be also be unhelpful evidence! Please discourage people from uploading footage/pictures in case they fall into this category, either for you or for someone else.
Be aware that the police may be watching social media. This can be used as evidence against you (or others) as it’s in a public forum, so don’t post specifics about your arrest or the events of the day.
Emails and private messages are different: they wouldn’t usually be used as evidence in court, although they could be monitored for intelligence purposes.