Broken string fixed but it still sounds off

It's a wound string on a classical guitar, by the clues. There's most likely a problem either with the winding, or the core - or both, that isn't easy to find, visually. As a stop gap, with no spare (why not?), maybe it's better than not having a D string at all, but the sensible thing to do is replace with a new one.

If that new one makes the others - especially the bottom three - sound dull, then replace all three. If the top three sound o.k, they won't need changing. Run a finger along their lengths, under the strings. Any lack of smoothness there is saying 'replace me too'.

To complete on @LaurencePayne 's answer: from the info you give I would assume you are talking about a classical guitar (edit: I now see the tags…), which strings are not ball-ended. If not, you would not have been able to put it back.

If that is correct, you took some length from the peg to compensate the amount you lost. Doing so, you brought some "fresh" string in the playing area where it actually vibrates. By "fresh" I mean unoxided, it does not mean that this part of the string is actually "like new": if the pegs are small, it is likely that the string has been affected by being wrapped around it.

Anyway, the fact is that you now have a string with two different resonating characteristic: the already played part, and the part you brought from the peg. This will surely sound different (how exactly, hard to say) than the previous string.

In all cases, if the string was worn to the point of breaking (and it's not even the treble E!) that it might be worth changing it, like Laurence said (or even the whole set for a more coherent sound, like @Tetsujin said ;) )!

Does "sharper as if it's acoustic" mean something about the tone-colour? I guess this is an electric guitar then? Are the pickup poles individually adjustable? Perhaps the string's just worn out. A worn-out string typically sounds duller rather than 'sharper' though.

Go on, lay out for a new string!