http://track-chinapost.com/result_global.php?code=LM429721915CN shows No shipping record. This means your seller never actually shipped anything yet. you might be scammed.

if you just got this number, You should push seller to ship the goods immediately. Tell him if you can not track real shipment data in next 3 days, you will open dispute to aliexpress/amazon/ebay/paypal against fraud.

If you have got this number for long time and paid with paypal/aliexpress, you should open dispute against fraud and claim refund.

http://track-chinapost.com/result_global.php?code=LM429721915CN still shows no record. Your seller has not shipped anything yet.

http://track-chinapost.com/result_china.php?order_no=LM429721915CN shows the parcel was shipped From China Post Guangzhou office to Mexico on Jan 21.

It is now some middle location between China Post system and Correos de Mexico system(possibly airline warehouse in Guangzhou ,China or customs warehouse in Mexico). You can not know exact situation when parcel is in such middle locations.

Such no-information stage might last 7 to 20 days(rush season can take 30 to 40 days) until Correos de Mexico gets the parcel from customs. Then Correos de Mexico website will show its new status with Mexico location.

Everything looks normal. Please wait some more days.

Your parcel seems to have problem.

If your can not get it by Mar 7, open dispute for lost parcel refund.