Try : t (20) → u (21) h (8) → i (9) m (13) → n (14) y (25) → z (26) l (12) → m (13) → “thmyl” → “uinzm” — no.
Could you provide more context — is this from a puzzle, a challenge, or just random text? If it’s from a known cipher, I can try a systematic frequency analysis. thmyl fry fayr mhkrt bdwn rwt
“thmyl” → “gsnbo” — not English. Possibly each word is a shifted version of a real word. Try : t (20) → u (21) h