What is happening
You had an indicator on your chart and now it is gone. In most cases it was removed by a template change, hidden, or the platform failed to load it — the file itself is usually still there.
Common causes
You switched or reset the chart template, which replaced everything on it. The indicator was removed via the indicators list. A platform update or crash cleared the chart. The indicator file was deleted, moved, or failed to compile. Or the indicator is set to show only on certain timeframes and you changed the timeframe.
Step-by-step fix
Re-add it: use the Insert menu or the Navigator panel to drag the indicator back onto the chart. Check the chart's indicators list to see if it is present but hidden. If it is missing from Navigator entirely, confirm the file is still in the correct indicators folder and refresh Navigator.
If you had a set-up you liked, load a saved template. If the file was deleted, reinstall it. Check the Experts/Journal tab for compile errors if it refuses to appear.
How to prevent it
Save a chart template once your indicators are arranged the way you want, so you can restore the whole layout in one click. Keep backups of custom indicator files. Be careful applying templates, as they overwrite the current chart.
Broker's fault or yours?
This is a local platform matter, not a broker issue. It is almost always recoverable with a re-add or a saved template.