I think step one is to recognize that sex drive naturally ebbs and flows throughout your life, there may not always be a reason. Additionally, it’s easy to think of it as a problem when society pushes the idea that you should be sexual to be normal. That being said, I can tell you miss it and I understand wanting it back!
What kinds of things have made you feel sexy or more sexual in the past? Maybe unrelated to your partner like romance novels, moving your body, certain types of self care, certain other activities? I know reading romance novels always gets my mind going and ups my sex drive. If you don’t like reading there’s also lots of audio sources like Dipsea or free stuff online. Overall I think connecting with your own sense of sensuality is your best bet. Maybe try something you’ve never done before like take a dance class or pick up a new hobby that would make you feel confident and cool.