i had a break [not 17 years, more 2 or 3] so i know what it's like to essentially start over. i would start by re-reading your favourite beginner book. not so much for definitions but to rekindle the spark you once had. i would also go over 'the basics' again; practice meditation, grounding, shielding, and the like [don't beat yourself up if it's not daily, i started every other day, because i tried doing the daily thing after 3 years of nothing, and i would go 4 days fine, then something would come up causing me to miss several days in a row.] also, on days you can't meditate, try simply take a few deep breaths just to centre yourself.
i also found the book The Goddess is in the Details by Deborah Blake the thing i personally needed to bring back my 'oomph' as it were. [of course i'm sure she's not for everyone, but i find her writing style similar to my own so i adore her] in her book she does skim over a few 'basic' points, but it's suppose to be an 'advanced' book for people who have read all the beginners guides and are now trying to figure out how to become a daily witch. she also includes activities, questions, and further reading at the end of each chapter.
best of luck to you.