Bro, try to understand what your saying in salaah. Comprehend what your saying in salaah... perhaps this will help you focus more... and recite out loud for fard part of the salaah.. (first 2 rakaah of fajr maghrib and isha)

if it still doesn't work... read Quran and Sunnah.... make sure you dont have any innovations in your worship.

or simply read Surah Baqarah once every day for 3 days.... every month. This will prevent shataan from entering your house.

W'salaamz,
Hamid