How to recover a deleted Git branch.

The short answer

Find the last commit of the deleted branch with git reflog, then recreate the branch at that SHA.

git reflog
# Find the SHA of the branch tip, then:
git checkout -b my-branch 9b7c4e2

If you deleted the branch moments ago, Git already told you the SHA. The output of the delete looks like Deleted branch my-branch (was 9b7c4e2). That short SHA is exactly what you pass to git checkout -b, and you can skip the reflog entirely.

Step by step

Do not create new commits or run garbage collection before you recover. The commits from the deleted branch are now unreferenced, and while Git keeps them for a grace period, git gc --prune=now would remove them. Recover first.

The full sequence

A branch reflog is deleted along with the branch, so you look in the HEAD reflog instead, which records every commit and checkout you made while that branch was current:

$ git reflog
a1b2c3d HEAD@{0}: checkout: moving from feature/reports to main
9b7c4e2 HEAD@{1}: commit: finish CSV report export
4d3a1f8 HEAD@{2}: commit: add report scaffold

# 9b7c4e2 was the tip of feature/reports before you left it.
# Confirm the history:
$ git log --oneline 9b7c4e2

# Recreate the branch at that commit:
$ git checkout -b feature/reports 9b7c4e2

When the reflog cannot help

If you never had the branch checked out in this clone (for example it only ever existed on a remote), or the reflog has already been pruned, git fsck can find commits that no branch points to any more:

# List commits that nothing references
git fsck --full --no-reflogs --unreachable --lost-found | grep commit

# Inspect a candidate to see if it is your branch tip
git show <commit-sha>

# Recreate the branch once you have identified it
git branch my-branch <commit-sha>

One more option worth remembering: if the branch was ever pushed, the remote still has it. A plain git fetch followed by git checkout -b my-branch origin/my-branch brings it back with no archaeology at all.

What this depends on

Branch recovery works because unreferenced commits survive in the object database for a grace window (30 days for unreachable objects by default) before garbage collection can remove them. The reflog is local and time-limited, it does not exist on a fresh clone, and once git gc --prune=now has run the objects can be gone. Recover sooner rather than later.