Upload the Russian .SRT file and this website tool will change it. You can turn everything into either lower case, upper case, sentence case or capitalise new word. Sentence case means that after a full stop, question mark or exclamation mark the next word will be capitalised. Alternatively capitalise new word means that every word will start with an uppercase letter. We also have the same Cyrillic tool for text or for TXT files. 
 

Examples:

Lower Case - столица россии - москва. москва большая.
Upper Case - СТОЛИЦА РОССИИ - МОСКВА. МОСКВА БОЛЬШАЯ.
Sentence Case - Столица России - Москва. Москва большая.
Capitalise New Word - Столица России - Москва. Москва Большая.