First thing... Take a deep breath, and take whatever measures you're familiar with to relax. The fix may be easy (rare, but hey sometimes you get lucky), but realistically it will probably take some time.
Next thing I would suggest, is disconnect that machine from the internet immediately (if you're using a wired connection just unplug the ethernet cable, if it's connected wirelessly then pull the wireless card if you can, or unplug the wireless router if your wireless is built into the motherboard). This is very important, especially if you have other machines on the network. You don't want it to spread. Nor do you want it repairing itself while you're killing it.
Your next step will be dependent upon your particular machine. Many OEMs can walk you through the process of either cleaning the machine of the ransomware, or scrubbing the machine entirely. It depends on the severity of the ransomware installed. But be aware that if it does entail scrubbing the entire machine (it might not, with any luck you won't have to reformat the hard drives) and as a result you'll lose any important files that you don't wish to lose.
Depending upon the OEM, and the severity of the malware, you might get off easy. Though even then it may take some time and patience. Most OEMs typically bend over backwards to help their customers in these situations though, and at the very least they'll typically send you recovery DVDs to return your machine to a virgin state if the ransomware has also compromised the recovery partition of your main hard drive.
I base these recommendations based upon your statement that you have a fixed income. You might be able to find a local service that can fix it for you, but typically you'll pay through the nose.