The "20A 12V" nomenclature on the switch isn't part of its part number, per se, but the electrical ratings of the switch (12VDC at up to 20A). 1117 may be a date code for when the switch was manufactured--the 17th week of 2011. It might also be some sort of a part number or abbreviated part number.
How many electrical terminals are on the switch, and what size/type are they? What are the dimensions of the switch? How does it mount to the panel it's in? If you find a switch with adequate electrical ratings, the same contact configuration, a compatible physical mounting and electrical terminations, you can use it; you aren't limited to the specific manufacturer and model.
If there are six electrical terminals on the switch, it's almost certainly a DPDT switch. If there are three, it would likely be an SPDT switch. If it is internally illuminated, add two additional terminals for that--which are not essential for a replacement for operating the shade. In any case, I assume it's a center-off momentary switch, meaning you have to hold it depressed on one side or the other to make things happen.