If you have zero to spend, then get used to using your phone as a speedometer and fill up your tank often so you don’t run out of fuel. There is no free, magic fix for this.
The entire instrument cluster may have failed. Something as simple as a power connection trace on the circuit board. It will take some time a probing to determine the cause. You might find a shop that repairs the part or you might be stuck with a dealer part IF it is even available for a 12 year old car. Sorry, that isn’t what you wanted to read.