Ensure to update the device flash firmware first before you may proceed to used this solution.
Nokia 5130 Memory Card not Detected Solution
There is a detector switch on MicroSD slot holder that triggers the device to activate the MMC circuit, check it if it is still working. You can read a voltage on that spots when the microSD is not inserted and then it dropped to 0 volts when the microSD card is inserted.
Check and ensure also the MicroSD card holderfree from dust, dirt, molds and oxidation build up, clean it if necessary.
Check the supply voltage of the MMC controller chip, If all of this voltages is okay, you may need to replace the MMC IC.