Welcome! Getting back on track is hard but you did it once so I'm certain you can do it again!
I recommend using an app to track everything you eat and drink. It is easy to underestimate what you are eating throughout the day and the app helps a lot. MyFitnessPal and Baritastic are used by many people on this site. Then go back to the basics: high protein, low carb and lots of water. The hardest part is getting started, but it gets easier the longer you stick with it.