Bhaktamar Strotra was composed by Muni Matongacharya in praise of Lord Adinath (The 1st Tirthankar of Jains). It comprises of 48 Shlokas. It is said to be one of the most powerful strotra of Jainism because of the way it has been created. If we put it simply, it is a matrix of seed words (beejakshar). When spoken continuously these strotras send vibrations bringing miraculous outcomes. Of course, good intentions are a prerequisite. Point to remember is that Bhaktamar is not a Mantra (Chants), it is a set of Strotra (hymns of praise). Since it is recited in praise so devotion is of utmost importance.
Bhaktamar strotra was composed by Shri Matugacharya in the Sixth or seventh century. The exact period is debated. Since then it has been held as one of the foremost scriptures and extremely sacred.
The legend is that Matunga Acharya was chained and imprisoned by King Bhoja for not obeying his orders. Matungacharya then composed the strotra in the praise of Lord Adinath comprising of 48 shlokas and as he recited each shloka his chains broke and at the end of the recital he was free from the prison.
Bhaktamar was written in the Devanagari script in the Sanskrit language initially, it has been translated in various languages since then. Bhaktamar strotra is said to cure ailments and help attain material wants and overcome fears. You have to have the utmost devotion for it, so as I said earlier that devotion is a prerequisite.
You can read the details and the Shlokas in the links given below.
https://ajay123.blogspot.com/2019/09/bhaktamar-stotra.html https://en.wikipedia.org/wiki/Bhaktamara_Stotra
http://www.tattvagyan.com/jain-stotra/bhaktamar-stotra/divine-composition/