Is it too late to sell shares for capital losses, after the year has ended?

I lost $5000 on some shares that are now worth 50 cents, and I haven't sold them.
I also just got laid off, and I plan on burning through my savings for 2 years.

So I would much rather claim this tax loss now instead of later.

I know that you can still e.g. invest in Roth IRA from for the previous year. Can I sell my shares and use the losses for the previous year too?