Funding your Argent X account from an Ethereum wallet
You can use Starknet official bridge to fund your wallet, for this, go to Starkgate and connect your Ethereum wallet and Argent X wallet.
Fill in the amount and click Transfer, then follow your L1 wallet's on-screen steps.
Check this article on withdrawal using Starkgate.
Funding your Argent X account from another blockchain/exchange
You can top up your Argent X wallet using Layerswap from your Ethereum mainnet addresses in Coinbase, Binance, Kraken wallet and many more exchanges to choose from.
For this navigate to https://www.layerswap.io/?destNetwork=starknet_mainnet and proceed with the on-screen instructions. You can also access Layerswap using Add funds menu in your Argent X wallet. Make sure you are using your Starknet mainnet wallet address and copy/paste it instead of typing it manually. You can copy your address in the assets tab right under the balance:
Please do not change the destination network (To field should remain Starknet)
Here you can find individual guides on using Layerswap based on your wallet/exchange: