The button may be faulty and the touchpad assembly may have to be replaced.
The touchpad is part of the keyboard bezel assembly.
Here’s a link to the [https://download.lenovo.com/pccbbs/mobiles_pdf/l450_hmm_en_sp40f12286_01.pdf|service manual] for your laptop.
Scroll to p.92 to view the necessary pre-requisite steps and then the procedure to remove/replace the keyboard bezel assembly so that the touchpad assembly can be removed/replaced.
Here’s a link to just one [https://www.ebay.com/itm/Genuine-New-for-Lenovo-ThinkPad-L440-L450-L460-L540-Touchpad-Cilickpad-Three-Key/123255008464?hash=item1cb2922cd0:g:k6gAAOSwojhbTVGY|supplier] of the replacement part. It is only shown to give an idea of the cost of the part. There are other suppliers online that may suit you better. Just search for ''Lenovo Thinkpad L450 touchpad assembly part'' to get results.
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In the interim you could try assigning the left mouse button function to another key. Here’s a [https://www.quora.com/How-do-I-assign-a-right-click-function-to-a-keyboard-key|link] that may be of some help.
Hi @christie1 ,
The button may be faulty and the touchpad assembly may have to be replaced.
The touchpad is part of the keyboard bezel assembly.
Here’s a link to the [https://download.lenovo.com/pccbbs/mobiles_pdf/l450_hmm_en_sp40f12286_01.pdf|service manual] for your laptop.
Scroll to p.92 to view the necessary pre-requisite steps and then the procedure to remove/replace the keyboard bezel assembly so that the touchpad assembly can be removed/replaced.
Here’s a link to just one [https://www.ebay.com/itm/Genuine-New-for-Lenovo-ThinkPad-L440-L450-L460-L540-Touchpad-Cilickpad-Three-Key/123255008464?hash=item1cb2922cd0:g:k6gAAOSwojhbTVGY|supplier] of the replacement part. It is only shown to give an idea of the cost of the part. There are other suppliers online that may suit you better. Just search for ''Lenovo Thinkpad L450 touchpad assembly part'' to get results.
Hopefully this is of some help.