Describe the visible text problem precisely
Wrong characters, empty boxes, a wrong language and late subtitles are different symptoms. If accented or non-Latin letters appear garbled while the words otherwise match the scene, preserve a screenshot of a non-sensitive example. Note the selected subtitle file and VLC version before changing anything.
Use a subtitle you are permitted to inspect and retain its original. For an original worked example, a name containing an accented letter may display as several unexpected characters. That is a different observation from a whole sentence arriving late. Moving the subtitle delay will not establish how the file’s bytes should be interpreted.
Compare the subtitle as text outside the player
Open a copy with a suitable text editor and inspect whether the same characters appear incorrectly there. Use the editor’s documented encoding information if available. Do not save over the original merely by opening it; some editors may rewrite encoding when a file is saved.
If the file is already unreadable in an appropriate editor, the source or its declared encoding needs investigation. If it is readable there but not in VLC, keep that comparison. Also confirm the selected file belongs to the actual video, since a correct encoding cannot fix a different language or mismatched subtitle edition.
Use the documented encoding setting carefully
VideoLAN’s Windows FAQ identifies the Default encoding option under Tools, Preferences and Subtitles/OSD for this symptom. Treat that as the documented desktop route and inspect the control in the installed build. Record the initial value before choosing an encoding justified by the subtitle’s actual provenance.
Reopen the same item and inspect the same words. Do not cycle randomly through many encodings while also changing fonts and timing. A controlled comparison should tell you whether one setting resolves the character interpretation. A font may be a separate issue if the text is correct but specific glyphs cannot be rendered.
Verify more than the first visible line
Check another passage containing the affected characters and confirm language and timing separately. Preserve the working value with the subtitle source details. If the result only improves some lines, keep an example of the remaining text rather than declaring the whole file repaired.
The expected outcome is readable text through an understood encoding route. This procedure does not translate subtitles or guarantee every style and font. If you later convert the subtitle to another encoding, work on a copy and test that saved artifact independently before replacing an original used by other players.
Questions answered
Will changing subtitle delay fix garbled letters?
No. Delay concerns timing. Inspect character encoding and rendering for unreadable text.
Should I try many encodings until one line looks better?
Use the subtitle’s actual encoding information where possible and compare several affected words. Keep one setting change at a time so the result remains explainable.
Sources & further reading
Official references for the subjects discussed. Service terms and device software can change.