Hi,
You may be out of luck.
Looking at the [https://download.lenovo.com/consumer/mobiles_pub/c740_14iml_15iml_hmm_201908.pdf|hardware maintenance manual] for the laptop, the touchscreen is integrated with the LCD panel. It cannot be individually replaced.
Go to p.42 to view the necessary pre-requisite steps and then the procedure to remove the LCD panel
The part number for a complete display assembly i.e. touchscreen + LCD panel is ''5D10S39587.''
Search online using the ''part number only'' to find suppliers that suit you best.