( If you're telling us your sound works fine but not YouTube,
then I have never seen a more stupid reply than answer # 3:
-- volume might be turned down
-- volume might have been muted
-- cookie might have kept it that way
-- could be due to slow connection
-- could be due to high traffic
-- watch during off peak hours
-- solution: purchase my downloader
By the way, 'cookies' are tiny files that websites plunk onto
your computer about your viewing preferences. They do not
affect sound whatsoever. )
I see questions like yours every couple days on Yahoo now.
So I did a whole lot of searching and reading, going through
dozens and dozens of websites, only to find out that there's
no definitive answer out there.
The only semblance of a partial solution that kind of worked
for some people would require you to either 1: mess around
with your registry (which I would be totally deadset against),
or 2: downloading some weird utility (which I am even more
against, because that kind of stuff is what probably created
your problem in the first place).
Thus, let me recommend what I advise so many other folks
when YouTube gets slow, stuck or weird: clear your "cache"
of all its "Cookies", 'History," and "Temporary Internet Files".
My infamous "CHTIF triple-cure" seems to resolve so many
people's YouTube problems, maybe it will "cure" yours also:
Internet Explorer 6:
→ Tools → Internet Options
→ Delete Cookies → OK
→ Delete Files → OK
→ Clear History → Yes
Internet Explorer 7:
→ Tools → Internet Options → Delete...
→ Delete files → Yes
→ Delete cookies → OK
→ Delete history → OK
→ Close (browsing history window)
→ Tools → Clear Private Data
[x] Browsing History
[x] Download History
[x] Saved Form and Search History
→ Clear Private Data Now
If that doesn't do the trick, here are some other suggestions:
-- If you've got "Google Web Accelerator" or anything similar,
get rid of it immediately. GWA destroys YouTube.
-- Long videos require both "Flash" and "Shockwave" to play
properly. Shockwave includes Flash, but not vice versa.
-- Avoid stupid add-ons, downloaders, and converters. There
are many Yahooligans who are really disguised salespeople.
If anyone suggests you acquire something, please note that
their "answer" probably has nothing to do with your question,
and that their products will most likely worsen your problem.
Besides, what kind of boffo and self-serving answer is:...[my
paraphrase] "Although you can't really listen or watch videos
properly, buy my downloader".
-- By default, every time you start a brand new session with
"Flash", the volume is set to zero. Maybe all you have to do
is click on the volume of the video player.
-- Who knows why it works, but sometimes things go better
when you change the web URL from "www . youtube . com"
to just "youtube . com" (or you can try "ca . youtube . com").
If you do find the "cause" and the "cure", I would very much
appreciate it if you could email me, either by clicking on my
avatar or writing to me at "firstname.lastname@example.org".
I wish you good luck, and hope that a part of my answer will
do the trick for you.