USB Blaster disapears from the hardware setup of the quartus prime programmer when I connect a com port with the teraterm using an FTDI usb to I2C adapter.

This is a common problem that occurs because the USB Blaster also uses an FTDI chip, which (somehow) causes a conflict.

Some possible solutions:

• do not use both at the same time: close the terminal before opening the programmer (but this seems not feasible for you)
• purchase a USB Blaster II: it does not use the FTDI chip, but it is not cheap
• There reports for other solutions, but they did not work very well for me, search this forum with keywords: "USB Blaster FTDI"