I believe that Synaptic would be the safest option if you don't want to
reinstall.
However, it would be much easier to reinstall if you could back up your data.
I had Trisquel running very nicely on a netbook with 500MB of RAM and a two
gig hard drive. It was unconventional, but not difficult:
Boot to the netinstall image. Install the base system. Do NOT install the
Trisquel desktop, Triskel desktop, or Trisquel-mini desktop.
Instead, sudo apt-get install xorg fluxbox jwm
I'm a bit rusty with writing tutorials, but I am just another ordinary user
without and IT degree and I would love to work on my communication skills. It
is a PLEASURE to help someone who is genuinely interested and motivated and
not just blindly swallowing Micro$oft and/or Apple(tm) propaganda.
Feel free to PM me if that is more comfortable for you. I opened my Trisquel
account with a gmail address when I didn't know any better, but the PMs go
directly to the openmailbox address I use now.