The feeling of inner emptiness or meaningless can come from weakness of love or attachment with Allah (SWT) and His most beloved servants, which is usually caused by less supplication and less spiritual practices like remembering Allah, night prayer (Tahajjud or Namaz Shab) and reciting Quran and Du'a with intention and thinking.
The cure of it is to remember the great reward for remembering Allah (SWT) and repeat it as many times as you can especially when are alone and during night and more specifically during Sojood. Repeating Salawaat enlighten the hear, and repeating Estighfaar cleans up the hear from the filth of sinful acts or thoughts.
Reciting Quran with a voice that you can easily hear is very useful.
Putting your hand on the head of an orphan and helping orphans and needy is very useful.
Seeking Du'a from your parents, doing more good to them and to your relatives is also very helpful in making your inner rich and make you feel satisfied and pleasant.