There are several very popular brackets which are no longer available, and although there are a few make do and mends, I’d recommend you consider renewing your track if you have any of these older brackets.
Having said the above, there are a few curtain tracks which have been upgraded and the new brackets are compatible with the old ones.
Swish standard lever lock brackets
The lever lock brackets are the latest version (as of late 2019) and have been around for over a decade now.
The old crescent foot brackets were much more difficult to use. They were slid in from the ends of the track and although they could be screwed directly to the wall, generally they came with wall mounting plates which enabled the track to be removed for cleaning more easily.
Not a particularly elegant solution. The video below demonstrate how the system worked
and here are a few photos of the old brackets.
Crescent foot brackets
and the wall mounting plates to which they slotted onto
Swish Twinglyde Valance Brackets
This was a popular spare part until around 2016 when it was discontinued by Sunflex who own the Swish brand in the UK. The end of an era for Swish as Sunflex incorporated them into their brand.
It was a neat system as the video below shows.
The curtain track brackets pictured below were still available around the end of 2018, though I no longer stock them
sometimes get asked for the return brackets, but to the best of my knowledge they were never available to retail.