Post Made Community Wiki by Martin
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Not using source control is asking for problems, even for a solo developer. The simple fact that you can edit ruthlessly without risking to lose anything makes up for the learning effort within weeks or days.

That said, if you can't convince your managers to introduce source control, do yourself a favor and at least use something like git or mercurial locally - if things blow up due to lack of source control, at least you won't be the one who did it.